{"id":308,"date":"2016-09-15T15:15:50","date_gmt":"2016-09-15T12:15:50","guid":{"rendered":"http:\/\/www.novelsmmigratom.tuiasi.ro\/?page_id=308"},"modified":"2016-09-16T13:38:02","modified_gmt":"2016-09-16T10:38:02","slug":"etapa-iv","status":"publish","type":"page","link":"http:\/\/www.novelsmmigratom.tuiasi.ro\/?page_id=308","title":{"rendered":"Etapa IV"},"content":{"rendered":"<h3 align=\"center\"><b>4.1 Eviden\u021bierea form\u0103rii reversibile a martensitei induse prin tensiune la probele 40_MA<\/b><\/h3>\n<h4 align=\"center\"><b>4.1.1. Ob\u021binerea geometriei probelor<\/b><\/h4>\n<p style=\"text-align: justify;\">Pentru experimente, probele sinterizate au fost laminate la cald, la 1060<sup>0<\/sup>C. Dup\u0103 \u0219ase treceri, grosimea probelor a sc\u0103zut de la 4 la 0,9 mm. Setul de probe 40_MA, laminate, au avut configura\u021biile conform <b>Fig.4.1<\/b>.<\/p>\n<p align=\"center\"><a href=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_1.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-227\" alt=\"Fig_4_1\" src=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_1.png\" width=\"340\" height=\"311\" srcset=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_1.png 340w, http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_1-300x274.png 300w\" sizes=\"(max-width: 340px) 100vw, 340px\" \/><\/a><\/p>\n<p align=\"center\"><b>Fig.4.1 Set de probe 40_MA, laminate, cu grosimi de 0,9 mm: (a) diverse probe <i>opm<\/i>; (b) seturi de probe OPM \u0219i D; (c) probe laminate, \u00eenainte de debitarea prin electroeroziune; (d) rezerva de probe 40_MA<\/b><\/p>\n<p style=\"text-align: justify;\">Dup\u0103 laminare, s-a procedat la debitarea probelor prin electroeroziune, cu ajutorul unei ma\u0219ini cu fir de Cu. Configura\u021biile corespunz\u0103toare din cele trei tipuri de probe au fost incluse \u00een Fig.4.1.<\/p>\n<h4 align=\"center\"><b>4.1.2. Ob\u021binerea martensitei induse prin temperatur\u0103<\/b><\/h4>\n<p style=\"text-align: justify;\">Dup\u0103 debitare, probele au fost grupate \u00een seturi compuse din 6 <i>OPM<\/i>, 5 <i>opm<\/i> \u0219i 4<i>D<\/i>, care au fost c\u0103lite prin punere \u00een solu\u021bie la temperaturi de 700, 800, 900, 1000 \u0219i respectiv 1100<sup>0<\/sup>C, cu men\u021binere 5 minute \u0219i r\u0103cire \u00een ap\u0103. Probele c\u0103lite au fost notate 40_MA_700, 40_MA_800; 40_MA_900, 40_MA_1000 \u0219i respectiv 40_MA_1100.<b><\/b><\/p>\n<p style=\"text-align: justify;\"><a href=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_2.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-323\" alt=\"Fig_4_2\" src=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_2.png\" width=\"523\" height=\"994\" \/><\/a><\/p>\n<p align=\"center\"><b style=\"line-height: 1.5;\">Fig.4.2 Identificarea martensitei induse termic prin XRD \u0219i OM la: (a) 40_MA_700; (b) 40_MA_800; (c) 40_MA_900; (d) 40_MA_1000 \u0219i (e) 40_MA_1100<\/b><\/p>\n<h4 align=\"center\"><b>4.1.3. \u00cencercarea la trac\u021biune<\/b><\/h4>\n<p style=\"text-align: justify;\">\u00cen vederea \u00eencerc\u0103rii la trac\u021biune s-au utilizat epruvete <i>OPM<\/i> care au fost cur\u0103\u021bate prin \u0219lefuire \u0219i lustruire, cu ajutorul unor ma\u0219ini speciale pentru aceste opera\u021bii, de tip METKON.<\/p>\n<p style=\"text-align: justify;\">\u00cencercarea la trac\u021biune s-a efectuat p\u00e2n\u0103 la rupere, pe o ma\u0219in\u0103 de tip INSTRON 3382, conform standardului ISO 6892-1:2009. Viteza de deplasare a traversei mobile a fost de 1 mm\/ min. \u00cen scopul determin\u0103rii comportamentului materialului analizat, <b>Fig.4.3<\/b> prezint\u0103 curbele de rupere caracteristice de rupere la trac\u021biune ale epruvetelor tratamente termic.<\/p>\n<p align=\"center\"><a href=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_3.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-326\" alt=\"Fig_4_3\" src=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_3.png\" width=\"392\" height=\"315\" srcset=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_3.png 392w, http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_3-300x241.png 300w\" sizes=\"(max-width: 392px) 100vw, 392px\" \/><\/a><\/p>\n<h4 align=\"center\"><b>4.1.4. Ob\u021binerea martensitei induse prin tensiune (MIT)<\/b><\/h4>\n<p style=\"text-align: justify;\">Inducerea prin tensiune a martensitei s-a efectuat printr-o \u00eenc\u0103rcare \u0219i o desc\u0103rcare la trac\u021biune. \u0218tiind c\u0103 nivelul maxim recomandat al deforma\u021biei este de 4 %, s-au utilizat datele din sec\u021biunea precedent\u0103 pentru ob\u021binerea unor alungiri remanente \u00een jur de maximum 4 % dar din ce \u00een ce mai mari, ceea ce \u00eenseamn\u0103 c\u0103 alungirea maxim\u0103 (total\u0103) a fost mai mare. Prin aceast\u0103 limitare s-a c\u0103utat s\u0103 se evite inducerea prin tensiune a unei cantit\u0103\u021bi suplimentare de martensit\u0103 \u03b1\u2019 (cvc). Prima serie exemplificatoare, de curbe de pretensionare, ob\u021binute la alungirea total\u0103 de 2% a probelor <i>OPM,<\/i> sunt date \u00een <b>Fig.4.4.<\/b><\/p>\n<p align=\"center\"><a href=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_4.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-329\" alt=\"Fig_4_4\" src=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_4.png\" width=\"636\" height=\"503\" srcset=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_4.png 636w, http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_4-300x237.png 300w\" sizes=\"(max-width: 636px) 100vw, 636px\" \/><\/a><\/p>\n<p align=\"center\"><b><i>Fig.4.4 Curbe de pretensionare cu 2 % a probelor 40_MA de tip OPM <\/i><\/b><\/p>\n<p style=\"text-align: justify;\">Se observ\u0103 toate cele cinci probe au rezistat pre-tension\u0103rii p\u00e2n\u0103 la alungirea maxim\u0103 relativ\u0103 de 2 %. \u00cen plus, cre\u0219terea temperaturii de tratament termic a produs sc\u0103derea tensiunii maxime atins\u0103 la o alungire de 2 %. Except\u00e2nd proba tratat\u0103 la 800<sup>0<\/sup>C, care s-a rupt, cre\u0219terea temperaturii de tratament termic a cauzat \u0219i cre\u0219terea alungirii remanente. Rezult\u0103 c\u0103, pentru alungirea maxim\u0103 de 2 %, cre\u0219terea temperaturii de tratament termic a produs accentuarea comportamentului plastic.<\/p>\n<p style=\"text-align: justify;\">Pentru a ilustra comportamentul la pretensionare prin trac\u021biune, p\u00e2n\u0103 la alungirea maxim\u0103 de 3 %, se prezint\u0103 \u00een <b>Fig.4.5<\/b> curbele tensiune-deforma\u021bie exemplificatoare ale probelor cu configura\u021bia <i>OPM<\/i>.<\/p>\n<p align=\"center\"><a href=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_5.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-332\" alt=\"Fig_4_5\" src=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_5.png\" width=\"382\" height=\"306\" srcset=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_5.png 382w, http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_5-300x240.png 300w\" sizes=\"(max-width: 382px) 100vw, 382px\" \/><\/a><\/p>\n<p align=\"center\"><b>Fig.4.5 Curbe de pretensionare p\u00e2n\u0103 la alungirea maxim\u0103 de 3 % a probelor <i>OPM<\/i><\/b><\/p>\n<p style=\"text-align: justify;\">\u00cen acest caz, cu excep\u021bia probelor tratate la 700 \u0219i la 1000<sup>0<\/sup>C, celelalte s-au rupt \u00een timpul pretension\u0103rii, \u00eenainte de atingerea unei alungiri relative de 3 %. Din cauza fragilit\u0103\u021bii excesive a probelor 40_MA tip <i>OPM<\/i>, pretension\u0103rile nu au mai continuat peste valoarea de 3 %.<\/p>\n<h4 align=\"center\"><b>4.1.5. Identificarea martensitei induse prin tensiune (MIT)<\/b><\/h4>\n<p style=\"text-align: justify;\">Pentru identificarea martensitei induse prin tensiune (MIT) la probele pre-tensionate, s-au utilizat: difrac\u021bia de raze X (XRD), microscopia optic\u0103 (OM) \u0219i microscopia electronic\u0103 cu baleiaj (SEM).<\/p>\n<p style=\"text-align: justify;\"><b><i>Analiza structural\u0103 calitativ\u0103 \u0219i cantitativ\u0103 prin difrac\u021bie de raze X<\/i><\/b> s-a efectuat pe por\u021biunea 2\u03b8 = 40 \u2013 100<sup>0<\/sup>. S-au luat \u00een considera\u021bie trei faze metalografice, austenita \u03b3-cfc \u0219i martensitele \u03b5-hc \u0219i \u03b1\u2019-cvc, pentru identificarea c\u0103rora s-au folosit datele din Tab.2.2, etapa a-II-a. Detaliile experimentale au fost prezentate \u00een sec\u021biunea 4.1.2.<\/p>\n<p style=\"text-align: justify;\">Prima serie de difractograme, ilustrat\u0103 \u00een <b>Fig. 4.6<\/b>, se refer\u0103 la probele tratate termic, nepretensionate.<\/p>\n<p align=\"center\"><a href=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_6.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-335\" alt=\"Fig_4_6\" src=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_6.png\" width=\"702\" height=\"452\" srcset=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_6.png 702w, http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_6-300x193.png 300w\" sizes=\"(max-width: 702px) 100vw, 702px\" \/><\/a><\/p>\n<p align=\"center\"><b>Fig.4.6 Difractograme de raze X ale probelor 40_MA tip <i>OPM<\/i> c\u0103lite prin punere \u00een solu\u021bie, \u00een stare ini\u021bial\u0103<\/b><\/p>\n<p style=\"text-align: justify;\">\u00cen continuare sunt prezentate micrografiile optice ale probelor 40_MA, tratate termic, la cele cinci temperaturi sus-men\u021bionate, exemplific\u00e2ndu-se efectele pretension\u0103rii a supra microstructurii observate. Dup\u0103 \u0219lefuire \u0219i lustruire, s-a efectuat un atac chimic cu o solu\u021bie de 1.2% K<sub>2<\/sub>S<sub>2<\/sub>O<sub>5<\/sub> + 1% NH<sub>4<\/sub>HF<sub>2<\/sub> in 100 ml ap\u0103 distilat\u0103. Micrografiile optice prezint\u0103 aspecte generale, tipice pentru structura aliajelor analizate \u0219i detalii ale structurilor respective, pe care sunt identificate pl\u0103cile care pot fi atribuite martensitei \u03b1\u2019 (cvc).<\/p>\n<p>\u00a0<a href=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_7.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-338\" alt=\"Fig_4_7\" src=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_7.png\" width=\"522\" height=\"590\" srcset=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_7.png 522w, http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_7-265x300.png 265w\" sizes=\"(max-width: 522px) 100vw, 522px\" \/><\/a><\/p>\n<p align=\"center\"><b>Fig.4.7 Micrografii optice tipice probelor 40_MA_700, \u00een lumin\u0103 polarizat\u0103: (a) aspect general al probei nedeformate; (b) detaliu cu pl\u0103ci de martensit\u0103 \u03b1\u2019, la proba pretensionat\u0103 cu 1,06 %; (c) aspect general al probei pretensionate cu 2,23 %; (d) detaliu al martensitei \u03b1\u2019, la proba pretensionat\u0103 cu 2,58 %; (e) aspect general al probei rupte la 3,2 %<\/b><\/p>\n<p style=\"text-align: justify;\">Din analiza micrografiilor optice, din Fig.4.7, s-a determinat grafic o valoare de <b><i>20 \u03bcm<\/i><\/b> pentru <b><i>granula\u021bia medie<\/i><\/b>. Odat\u0103 cu cre\u0219terea temperaturii de tratament termic, se observ\u0103 apari\u021bia maclelor de recoacere, sub forma unor benzi paralele, de contrast diferit fa\u021b\u0103 de matricea austenitic\u0103 \u00eenconjur\u0103toare. Martensita \u03b5 (hc), estimat\u0103 la aprox. 15 %, apare sub form\u0103 de pl\u0103ci foarte sub\u021biri care nu se pot observa, clar, prin OM.<\/p>\n<p style=\"text-align: justify;\">Deoarece pl\u0103cile de martensit\u0103 \u03b5(hc) sunt relativ greu de observat \u0219i devin sesizabile doar la puteri foarte mari de m\u0103rire, se prezint\u0103, \u00een continuare, rezultatele ob\u021binute prin analiz\u0103 SEM.<\/p>\n<p align=\"center\"><a href=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_8.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-341\" alt=\"Fig_4_8\" src=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_8.png\" width=\"429\" height=\"686\" srcset=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_8.png 429w, http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_8-187x300.png 187w\" sizes=\"(max-width: 429px) 100vw, 429px\" \/><\/a><\/p>\n<p align=\"center\"><b>Fig.4.8 Micrografii SEM caracteristice probelor 40_MA_700: (a) \u00een stare ini\u021bial\u0103; (b) pretensionat\u0103 cu 1,06 %; (c) pretensionat\u0103 cu 2,23 %; (d) pretensionat\u0103 cu 2,58 %; (e) pretensionat\u0103 cu 3,2 %<\/b><\/p>\n<h4 align=\"center\"><b>4.1.6. Reversia martensitei induse prin tensiune<\/b><\/h4>\n<p style=\"text-align: justify;\">Pentru ilustrarea reversiei martensitei induse prin tensiune s-au efectuat experimente repetate, de generare a efectului de memoria formei (EMF) cu revenire liber\u0103, \u00een scopul educ\u0103rii AMF, asociate cu analiza cinematografic\u0103 a deplas\u0103rii probei, dup\u0103 aceea\u0219i procedur\u0103 ca \u00een etapa a-III-a. Au fost selectate 2 lamele de aliaj 40_MA, laminate la cald, care nu au fost tratate termic. Probele au fost ajustate, astfel \u00eenc\u00e2t s\u0103 aib\u0103 muchii paralele care \u00een final au fost te\u0219ite, pentru a nu genera fisuri. Pentru u\u0219urarea deform\u0103rii plastice, probele au fost \u0219lefuite \u0219i lustruite. Cu ajutorul unor dispozitive speciale, aceast\u0103 prob\u0103 a fost rulat\u0103, treptat, imprim\u00e2ndu-i-se o form\u0103 \u201erece\u201d curbat\u0103. Ansamblul experimental \u0219i forma \u201erece\u201d, ini\u021bial\u0103, a probei \u201eneeducate\u201d pot fi observate \u00een <b>Fig.4.9<\/b>.<\/p>\n<p align=\"center\"><a href=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_9.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-344\" alt=\"Fig_4_9\" src=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_9.png\" width=\"523\" height=\"294\" srcset=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_9.png 523w, http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_9-300x168.png 300w\" sizes=\"(max-width: 523px) 100vw, 523px\" \/><\/a><\/p>\n<p align=\"center\"><b>Fig.4.9 Ansamblul de \u00a040_MA, laminat\u0103 la cald \u0219i netratat\u0103, probelor utilizate pentru experimentele cu efect de memoria formei (EMF) cu revenire liber\u0103<\/b><\/p>\n<p style=\"text-align: justify;\">Dup\u0103 imprimarea formei reci, proba a fost fixat\u0103 \u00eentr-un dispozitiv \u0219i \u00eenc\u0103lzit\u0103 cu un arz\u0103tor mobil, cu flac\u0103r\u0103. Prin EMF cu revenire liber\u0103, proba \u0219i-a recuperat par\u021bial forma cald\u0103, mai apropiat\u0103 de cea rectilinie. Temperatura probei a fost m\u0103surat\u0103 cu un multimetru digital, dotat cu termocuplu, care a fost fixat pe suprafa\u021ba inferioar\u0103 a probei, neexpus\u0103 la flac\u0103ra arz\u0103torului, conform Fig.4.9. Cu ajutorul unei camere digitale, au fost filmat\u0103 deplasarea cap\u0103tului probei, concomitent cu varia\u021bia temperaturii. Dup\u0103 atingerea unei temperaturi de cca. 400<sup>0<\/sup>C, s-a considerat c\u0103 reversia martensitei este complet\u0103. S-a \u00eendep\u0103rtat flac\u0103r\u0103 \u0219i s-a aplicat r\u0103cire cu ap\u0103. Apoi proba a fost deformat\u0103 din nou \u0219i experimentul a fost repetat, pentru a se ob\u021bine efectul de educare. Dup\u0103 cinci cicluri, s-a observat efectul de educare eviden\u021biat prin cre\u0219terea vitezei de deplasare \u0219i amplificarea deforma\u021biei recuperate. Filmele \u00eenregistrate au fost analizate cadru-cu-cadru, ob\u021bin\u00e2ndu-se imagini ale pozi\u021biei succesive a probei \u00een timpul \u00eenc\u0103lzirii, la diverse temperaturi. <b>Fig.4.10<\/b> prezint\u0103 pozi\u021biile ini\u021bial\u0103 \u0219i final\u0103, \u00eenregistrate \u00een timpul primului ciclu de educare.<\/p>\n<p align=\"center\"><a href=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_10.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-347\" alt=\"Fig_4_10\" src=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_10.png\" width=\"523\" height=\"148\" srcset=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_10.png 523w, http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_10-300x84.png 300w\" sizes=\"(max-width: 523px) 100vw, 523px\" \/><\/a><\/p>\n<p align=\"center\"><b>Fig.4.10 Imagini din timpul \u00eenc\u0103lzirii \u00een cadrul primului ciclu de educare prin EMF cu revenire liber\u0103 a unei probe lamelare din 40_MA laminat\u0103 la cald: (a) la temperatura de 26<sup>0<\/sup>C; (b) la temperatura de 254<sup>0<\/sup>C<\/b><\/p>\n<p style=\"text-align: justify;\">Se poate observa c\u0103 dup\u0103 14 secunde temperatura a crescut de la 26 la 254<sup>0<\/sup>C iar cap\u0103tul liber al probei s-a deplasat de la h<sub>26<\/sub> = 138 mm la h<sub>254<\/sub> = 153 mm, cu valoarea \u0394h<sub>1<\/sub> = 15 mm, viteza de deplasare fiind de cca. 1,07 mm\/s. \u00cen <b>Fig.4.11<\/b> se prezint\u0103 rezultatele semnificative ale celui de-al doilea ciclu de educare.<\/p>\n<p>\u00a0<a href=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_11.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-350\" alt=\"Fig_4_11\" src=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_11.png\" width=\"523\" height=\"147\" srcset=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_11.png 523w, http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_11-300x84.png 300w\" sizes=\"(max-width: 523px) 100vw, 523px\" \/><\/a><\/p>\n<p align=\"center\"><b>Fig.4.11 Imagini din timpul \u00eenc\u0103lzirii \u00een cadrul celui de-al doilea ciclu de educare prin EMF cu revenire liber\u0103 a unei probe lamelare din 40_MA laminat\u0103 la cald: (a) la temperatura de 24<sup>0<\/sup>C; (b) la temperatura de 294<sup>0<\/sup>C<\/b><\/p>\n<p style=\"text-align: justify;\">Se poate observa c\u0103 forma rece, imprimat\u0103 la \u00eenceputul celui de-al doilea ciclu, este la fel de \u00eencovoiat\u0103 (deformat\u0103) ca forma rece de la \u00eenceputul primului ciclu. \u00cen acest caz, temperatura a crescut de la 24 la 294<sup>0<\/sup>C \u00een 23 de secunde iar deplasarea total\u0103 a fost \u0394h<sub>2<\/sub> = h<sub>294<\/sub>-h<sub>24<\/sub> = 16 mm, cu o vitez\u0103 de cca. 0,7 mm\/s.<\/p>\n<p style=\"text-align: justify;\">Repetarea cicl\u0103rii a dus, \u00een ciclului al treilea, la pozi\u021biile extreme deplasate spre valori mai mici, dup\u0103 cum se observ\u0103 din <b>Fig.4.12<\/b>. \u00cen acest caz, forma rece este \u00een mod evident mai deformat\u0103, deoarece \u00een\u0103l\u021bimea caracteristic\u0103 acesteia este h<sub>28<\/sub> = 115 mm. Dup\u0103 26 s, temperatura a crescut de la 28 la 163<sup>0<\/sup>C iar \u00een\u0103l\u021bimea cap\u0103tului liber a atins h<sub>163<\/sub> = 134 mm. Deplasarea total\u0103 a fost \u0394h<sub>3<\/sub> = 19 mm iar viteza de cca. 0,73 mm\/s.<\/p>\n<p>\u00a0<a href=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_12.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-353\" alt=\"Fig_4_12\" src=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_12.png\" width=\"523\" height=\"145\" srcset=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_12.png 523w, http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_12-300x83.png 300w\" sizes=\"(max-width: 523px) 100vw, 523px\" \/><\/a><\/p>\n<p align=\"center\"><b>Fig.4.12 Imagini din timpul \u00eenc\u0103lzirii \u00een cadrul celui de-al treilea ciclu de educare prin EMF cu revenire liber\u0103 a unei probe lamelare din 40_MA laminat\u0103 la cald: (a) la temperatura de 28<sup>0<\/sup>C; (b) la temperatura de 163<sup>0<\/sup>C<\/b><\/p>\n<p style=\"text-align: justify;\">Continuarea cicl\u0103rii a produs o cre\u0219tere clar\u0103 a deforma\u021biei admise de prob\u0103 la imprimarea formei reci, ceea ce a dus la cre\u0219terea deplas\u0103rii maxime, de la h<sub>29<\/sub> = 116 mm la h<sub>248<\/sub> = 136,5 mm, conform <b>Fig.4.13<\/b>.<\/p>\n<p>\u00a0<a href=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_13.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-356\" alt=\"Fig_4_13\" src=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_13.png\" width=\"522\" height=\"147\" srcset=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_13.png 522w, http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_13-300x84.png 300w\" sizes=\"(max-width: 522px) 100vw, 522px\" \/><\/a><\/p>\n<p align=\"center\"><b>Fig.4.13 Imagini din timpul \u00eenc\u0103lzirii \u00een cadrul celui de-al patrulea ciclu de educare prin EMF cu revenire liber\u0103 a unei probe lamelare din 40_MA laminat\u0103 la cald: (a) la temperatura de 29<sup>0<\/sup>C; (b) la temperatura de 248<sup>0<\/sup>C<\/b><\/p>\n<p style=\"text-align: justify;\">Trebuie remarcat c\u0103 \u00een acest caz s-a produs o rupere a probei educate \u00eens\u0103 educarea a continuat, cu o prob\u0103 scrutat\u0103 cu cca 10 mm. \u00cen aceste condi\u021bii se observ\u0103 clar, prin compararea Fig.4.25(a) cu 4.26(a) c\u0103 forma rece din ciclul al patrulea este mai deformat\u0103 dec\u00e2t cea din ciclul al treilea. Deplasarea total\u0103 de 20,5 mm s-a produs \u00een 17 s, cu o vitez\u0103 de peste 1,2 mm\/s. Pozi\u021biile caracteristice celui de-al cincilea ciclu de educare sunt ilustrate \u00een <b>Fig.4.14<\/b>.<\/p>\n<p>\u00a0<a href=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_14.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-359\" alt=\"Fig_4_14\" src=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_14.png\" width=\"523\" height=\"146\" srcset=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_14.png 523w, http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_14-300x83.png 300w\" sizes=\"(max-width: 523px) 100vw, 523px\" \/><\/a><\/p>\n<p align=\"center\"><b>Fig.4.14 Imagini din timpul \u00eenc\u0103lzirii \u00een cadrul celui de-al cincilea ciclu de educare prin EMF cu revenire liber\u0103 a unei probe lamelare din 40_MA laminat\u0103 la cald: (a) la temperatura de 28<sup>0<\/sup>C; (b) la temperatura de 236<sup>0<\/sup>C<\/b><\/p>\n<p style=\"text-align: justify;\">Se observ\u0103 c\u0103 h<sub>28<\/sub> = 110 mm iar h<sub>236<\/sub> = 134 mm, ceea ce d\u0103 o curs\u0103 total\u0103 de 24 mm, care s-a produs \u00een 14 s, cu o vitez\u0103 de peste 1,71 mm\/s.<\/p>\n<p align=\"center\"><b>4.1.7. Corelarea rezultatelor legate de formarea \u0219i reversia MIT<\/b><\/p>\n<p style=\"text-align: justify;\">Corelarea rezultatelor legate de formarea \u0219i reversia martensitei s-a realizat pe baza datelor din Tab.4.4., ob\u021binute pe baza difractogramelor de raze X, din Fig.4.6-4.11. Reprezentare cumulat\u0103 a acestora este prezentat\u0103 \u00een <b>Fig.4.15<\/b>.<\/p>\n<p align=\"center\"><a href=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_15.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-362\" alt=\"Fig_4_15\" src=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_15.png\" width=\"670\" height=\"499\" srcset=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_15.png 670w, http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_15-300x223.png 300w\" sizes=\"(max-width: 670px) 100vw, 670px\" \/><\/a><\/p>\n<p align=\"center\"><b>Fig.4.15 Diagram\u0103 cumulativ\u0103 de varia\u021bie a cantit\u0103\u021bilor relative ale celor trei faze, conform Tab.4.4<\/b><\/p>\n<p style=\"text-align: justify;\">Se poate remarca diferen\u021ba clar\u0103 \u00eentre cantitatea de faz\u0103 \u03b1\u2019 (cvc) \u0219i cantit\u0103\u021bile de faz\u0103 \u03b5 (hc) \u0219i \u03b3 (cfc). Prin intermediul unor diagrame 3-D, care ilustreaz\u0103 varia\u021biile cantit\u0103\u021bilor procentuale ale celor trei faze, \u03b1\u2019, \u03b5 \u0219i \u03b3 \u00een func\u021bie de temperatura c\u0103lirii de punere \u00een solu\u021bie, s-a realizat corelarea rezultatelor legate de formarea \u0219i reversia martensitei induse prin tensiune<b>. Fig.4.16, 4.17<\/b> \u0219i <b>4.18<\/b> prezint\u0103 varia\u021biile cantitative ale fazelor \u03b1\u2019, \u03b5 \u0219i respectiv \u03b3 \u00een func\u021bie de temperatura de tratament termic \u0219i de gradul de pretensionare.<\/p>\n<p align=\"center\"><a href=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_16.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-365\" alt=\"Fig_4_16\" src=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_16.png\" width=\"733\" height=\"550\" srcset=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_16.png 733w, http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_16-300x225.png 300w\" sizes=\"(max-width: 733px) 100vw, 733px\" \/><\/a><\/p>\n<p align=\"center\"><b>Fig.4.16 Varia\u021biile cantit\u0103\u021bii de martensit\u0103 \u03b1\u2019 \u00een func\u021bie de temperatura de c\u0103lire de punere \u00een solu\u021bie \u0219i de alungirea aplicat\u0103<\/b><\/p>\n<p align=\"center\"><a href=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_17.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-368\" alt=\"Fig_4_17\" src=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_17.png\" width=\"392\" height=\"289\" srcset=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_17.png 392w, http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_17-300x221.png 300w\" sizes=\"(max-width: 392px) 100vw, 392px\" \/><\/a><\/p>\n<p align=\"center\"><b>Fig.4.17 Varia\u021biile cantit\u0103\u021bii de martensit\u0103 \u03b5 \u00een func\u021bie de temperatura de c\u0103lire de punere \u00een solu\u021bie \u0219i de alungirea aplicat\u0103<\/b><\/p>\n<p align=\"center\"><a href=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_18.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-371\" alt=\"Fig_4_18\" src=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_18.png\" width=\"381\" height=\"282\" srcset=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_18.png 381w, http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_18-300x222.png 300w\" sizes=\"(max-width: 381px) 100vw, 381px\" \/><\/a><\/p>\n<p align=\"center\"><b>Fig.4.18 Varia\u021biile cantit\u0103\u021bii de austenit\u0103 \u03b3 \u00een func\u021bie de temperatura de c\u0103lire de punere \u00een solu\u021bie \u0219i de alungirea aplicat\u0103<\/b><\/p>\n<p>Concluziile acestui studiu corelativ sunt urm\u0103toarele:<\/p>\n<ul>\n<li style=\"text-align: justify;\">Probele de Fe-14Mn-6Si-9Cr-5Ni (% m) ob\u021binute prin metalurgia pulberilor \u0219i con\u021bin\u00e2nd 40 % pulbere aliat\u0103 mecanic, au prezentat cantit\u0103\u021bi ini\u021biale variind \u00eentre aproape 56 \u0219i peste 78 % pentru martensita \u03b1\u2019 \u0219i \u00eentre 15 \u0219i 21 % pentru martensit\u0103 \u03b5 (hc), ambele fiind induse termic;<\/li>\n<li style=\"text-align: justify;\">Cre\u0219terea alungirii aplicate a fost \u00eenso\u021bit\u0103 de tendin\u021be globale de cre\u0219tere ale cantit\u0103\u021bilor de martensit\u0103 \u03b1\u2019 \u0219i austenit\u0103 \u03b3 \u0219i de sc\u0103dere a martensitei \u03b5.<\/li>\n<\/ul>\n<p align=\"center\"><b>4.1.8. Analiza mecano-dinamic\u0103 (DMA) la scanare termic\u0103<\/b><\/p>\n<p style=\"text-align: justify;\">Analiza mecano-dinamic\u0103 (DMA) s-a f\u0103cut pe probe de tip D (Fig.4.1), cu un termograf DMA 242 E NETZSCH. Probele 40_MA au fost analizate la frecven\u021ba de 1 Hz \u0219i amplitudinea de 20 \u00b5m, cu dispozitivul de \u00eencovoiere \u00een trei puncte, fiind \u00eenc\u0103lzite sub atmosfer\u0103 protectoare p\u00e2n\u0103 la 400<sup>0<\/sup>C. Termogramele DMA au \u00eenregistrat varia\u021biile modulului de \u00eenmagazinare (E\u2019) \u0219i ale frec\u0103rii interne (tan d) \u00een func\u021bie de temperatur\u0103 (T), pentru probele tratate termic la, respectiv, 700, 800, \u2026, 1100<sup>0<\/sup>C.<\/p>\n<p align=\"center\"><a href=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_19.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-374\" alt=\"Fig_4_19\" src=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_19.png\" width=\"522\" height=\"257\" srcset=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_19.png 522w, http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_19-300x147.png 300w\" sizes=\"(max-width: 522px) 100vw, 522px\" \/><\/a><\/p>\n<p align=\"center\"><b>Fig.4.19 Termograme DMA ale probelor 40_MA_700<\/b><\/p>\n<p style=\"text-align: justify;\">\u00cen conformitate cu observa\u021bii efectuate pe probe de AMF tip Fe-Mn-Si care prezentau ambele forme de martensit\u0103, \u03b1\u2019 (cvc) \u0219i \u03b5 (hc) \u0219i cu rezultatele din etapa 3, 2015, se consider\u0103 c\u0103 cele dou\u0103 maxime ale frec\u0103rii interne situate la A<sub>50<\/sub><sup>\u03b1\u2019<\/sup> \u0219i A<sub>50<\/sub><sup>\u03b5<\/sup> corespund transform\u0103rilor \u03b1\u2019 (cvc) \u2192 \u03b3 (cfc) \u0219i respectiv \u03b5 (hc) \u2192 \u03b3 (cfc). Cu \u0394E\u2019 s-a notat cre\u0219terea modulului de \u00eenmagazinare asociat\u0103 cu transformarea antiferomagnetic \u2192 paragmagnetic a martensitei \u03b5, care se produce la temperatura Neel.<\/p>\n<p align=\"center\"><a href=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_20.png\"><img loading=\"lazy\" class=\"aligncenter size-large wp-image-377\" alt=\"Fig_4_20\" src=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_20-1024x504.png\" width=\"604\" height=\"297\" srcset=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_20-1024x504.png 1024w, http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_20-300x147.png 300w\" sizes=\"(max-width: 604px) 100vw, 604px\" \/><\/a><\/p>\n<p align=\"center\"><b>Fig.4.20 Termograme DMA ale probelor 40_MA_800<\/b><\/p>\n<p style=\"text-align: justify;\">\u00cen <b>Fig.4.20<\/b> c\u0103, la proba 40_MA_800 transformarea antiferomagnetic \u2192 paragmagnetic a martensitei \u03b5 este foarte slab\u0103, deoarece nu s-a putut eviden\u021bia o cre\u0219tere sesizabil\u0103 a modulului de \u00eenmagazinare, E\u2019. Aceast\u0103 situa\u021bie poate fi asociat\u0103 cu valoarea relativ redus\u0103, de cca. 0,0196, a celui de-al doilea maxim al frec\u0103rii interne, localizat la A<sub>50<\/sub><sup>\u03b5<\/sup>. Pe de alt\u0103 parte, \u00een Fig.4.21 \u0219i 4.22 se observ\u0103 c\u0103 la probele 40_MA_900 \u0219i 40_MA_1000 lipse\u0219te primul maxim al tan d \u0219i nu s-a putut eviden\u021bia transformarea \u03b1\u2019 (cvc) \u2192 \u03b3 (cfc).<\/p>\n<p align=\"center\">\u00a0<a href=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_21.png\"><img loading=\"lazy\" class=\"aligncenter size-large wp-image-380\" alt=\"Fig_4_21\" src=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_21-1024x504.png\" width=\"604\" height=\"297\" srcset=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_21-1024x504.png 1024w, http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_21-300x147.png 300w\" sizes=\"(max-width: 604px) 100vw, 604px\" \/><\/a><\/p>\n<p align=\"center\"><b>Fig.4.21 Termograme DMA ale probelor 40_MA_900<\/b><\/p>\n<p align=\"center\"><a href=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_22.png\"><img loading=\"lazy\" class=\"aligncenter size-large wp-image-383\" alt=\"Fig_4_22\" src=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_22-1024x504.png\" width=\"604\" height=\"297\" srcset=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_22-1024x504.png 1024w, http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_22-300x147.png 300w\" sizes=\"(max-width: 604px) 100vw, 604px\" \/><\/a><\/p>\n<p align=\"center\"><b>Fig.4.22 Termograme DMA ale probelor 40_MA_1000<\/b><\/p>\n<p align=\"center\"><a href=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_23.png\"><img loading=\"lazy\" class=\"aligncenter size-large wp-image-386\" alt=\"Fig_4_23\" src=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_23-1024x504.png\" width=\"604\" height=\"297\" srcset=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_23-1024x504.png 1024w, http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_23-300x147.png 300w\" sizes=\"(max-width: 604px) 100vw, 604px\" \/><\/a><\/p>\n<p align=\"center\"><b>Fig.4.23 Termograme DMA ale probelor 40_MA_1100<\/b><\/p>\n<p align=\"center\"><b>4.2. Studiul efectelor alierii mecanice asupra migra\u021biei atomice<\/b><\/p>\n<p style=\"text-align: justify;\">Pentru a studia efectele alierii mecanice, c\u00e2te cinci grupuri de probe de tip <i>D,<\/i> din fiecare dintre cele cinci categorii analizate, 0_MA, 10_MA, \u2026, 40_MA, cu propor\u021bii de pulbere aliat\u0103 mecanic variind \u00eentre 0 \u0219i respectiv 40 %, care au fost fiecare c\u0103lite prin punere \u00een solu\u021bie la c\u00e2te cinci temperaturi \u00eentre 700, 800, \u2026, 1100<sup>0<\/sup>C, au fost supuse investiga\u021biilor efectuate prin DMA, la temperatur\u0103 constant\u0103, cu varia\u021bia amplitudinii (baleiere de amplitudine), de la 0,1 \u03bcm la valoarea maxim\u0103 de 200 \u03bcm, cu o frecven\u021b\u0103 de 1 Hz.<\/p>\n<p style=\"text-align: justify;\">\u00cen Fig.4.24 sunt prezentate rezultatele baleierii de amplitudine pentru proba 0_MA_700. Cele trei temperaturi de baleiere au fost T<sub>1<\/sub> = RT, T<sub>2<\/sub> = 325 \u0219i T<sub>3<\/sub> = 400<sup>0<\/sup>C. Pe diagrame se prezint\u0103 rezultatele primei baleieri (linie continu\u0103) ale celei de-a doua (linie \u00eentrerupt\u0103) \u0219i a treia (linie-punct) precum \u0219i media celor trei baleieri (linie dou\u0103 puncte).<\/p>\n<p>\u00a0<a href=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_24.png\"><img loading=\"lazy\" class=\"aligncenter size-large wp-image-389\" alt=\"Fig_4_24\" src=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_24-692x1024.png\" width=\"604\" height=\"893\" srcset=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_24-692x1024.png 692w, http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_24-202x300.png 202w, http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_24.png 1000w\" sizes=\"(max-width: 604px) 100vw, 604px\" \/><\/a><\/p>\n<p style=\"text-align: center;\">\u00a0<b>Fig.4.24 Termograme DMA ale probelor 0_MA_700, \u00eenregistrate la baleierea de amplitudine la: (a) temperatura T<sub>1<\/sub> = RT; (b) temperatura T<sub>2<\/sub> = 325<sup>0<\/sup>C \u0219i (c) temperatura T<sub>3<\/sub> = 400<sup>0<\/sup>C<\/b><\/p>\n<p style=\"text-align: justify;\">Se observ\u0103 tendin\u021ba de majorare, at\u00e2t a frec\u0103rii interne c\u00e2t \u0219i a modulului de elasticitate, de la o baleiere la alta. \u00cen general, rezultatele celei de-a doua baleieri sunt mult diferite fa\u021b\u0103 de prima. La cea de-a treia baleiere, diferen\u021bele sunt mult mai mici, fa\u021b\u0103 e cea de-a doua. Odat\u0103 cu cre\u0219terea amplitudinii de deformare este evident\u0103 tendin\u021ba de sc\u0103dere a frec\u0103rii interne, la toate cele trei temperaturi de baleiere. Pe de alt\u0103 parte, modulul de elasticitate tinde s\u0103 creasc\u0103, la cre\u0219terea amplitudinii. Se remarc\u0103 prezen\u021ba unui palier la varia\u021bia modulului de elasticitate \u00een func\u021bie de amplitudine, \u00een cazul baleierii la temperatura camerei.<\/p>\n<p style=\"text-align: justify;\">Pentru o mai bun\u0103 eviden\u021biere a efectelor propor\u021biei de pulbere aliat\u0103 mecanic, s-au prezentat varia\u021biile valorii maxime a modulului de elasticitate, E\u2019 \u0219i a valorii medii a frec\u0103rii interne, tand<sub>med<\/sub>, \u00een Fig.4.25.<\/p>\n<p>\u00a0<a href=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_25.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-392\" alt=\"Fig_4_25\" src=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_25.png\" width=\"523\" height=\"124\" srcset=\"http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_25.png 523w, http:\/\/www.novelsmmigratom.tuiasi.ro\/wp-content\/uploads\/2016\/09\/Fig_4_25-300x71.png 300w\" sizes=\"(max-width: 523px) 100vw, 523px\" \/><\/a><\/p>\n<p style=\"text-align: center;\"><b>Fig.4.25 Ilustrare grafic\u0103 a efectului propor\u021biei de pulbere aliat\u0103 mecanic asupra varia\u021biei valorii maxime a modulului de elasticitate, E\u2019 \u0219i a valorii medii a frec\u0103rii interne, tan<\/b><b>d<\/b><b><sub>med<\/sub><\/b><b> \u00een func\u021bie de temperatura de tratament termic, ob\u021binute prin baleierea de amplitudine, conform Fig.4.39-4.63: (a) 0_MA; (b) 20_MA; (c) 40_MA<\/b><\/p>\n<p style=\"text-align: justify;\"><b>\u00a0<\/b>Se remarc\u0103, \u00een general, tendin\u021ba probelor analizate de a prezenta cele mai mari valori ale modulului maxim \u0219i cele mai mici valori ale frec\u0103rii medii, atunci c\u00e2nd sunt m\u0103surate la temperatura camerei (RT).<\/p>\n","protected":false},"excerpt":{"rendered":"<p>4.1 Eviden\u021bierea form\u0103rii reversibile a martensitei induse prin tensiune la probele 40_MA 4.1.1. Ob\u021binerea geometriei probelor Pentru experimente, probele sinterizate au fost laminate la cald, la 10600C. Dup\u0103 \u0219ase treceri, grosimea probelor a sc\u0103zut de la 4 la 0,9 mm. Setul de probe 40_MA, laminate, au avut configura\u021biile conform Fig.4.1. Fig.4.1 Set de probe 40_MA, [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":99,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":[],"_links":{"self":[{"href":"http:\/\/www.novelsmmigratom.tuiasi.ro\/index.php?rest_route=\/wp\/v2\/pages\/308"}],"collection":[{"href":"http:\/\/www.novelsmmigratom.tuiasi.ro\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"http:\/\/www.novelsmmigratom.tuiasi.ro\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"http:\/\/www.novelsmmigratom.tuiasi.ro\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.novelsmmigratom.tuiasi.ro\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=308"}],"version-history":[{"count":6,"href":"http:\/\/www.novelsmmigratom.tuiasi.ro\/index.php?rest_route=\/wp\/v2\/pages\/308\/revisions"}],"predecessor-version":[{"id":413,"href":"http:\/\/www.novelsmmigratom.tuiasi.ro\/index.php?rest_route=\/wp\/v2\/pages\/308\/revisions\/413"}],"up":[{"embeddable":true,"href":"http:\/\/www.novelsmmigratom.tuiasi.ro\/index.php?rest_route=\/wp\/v2\/pages\/99"}],"wp:attachment":[{"href":"http:\/\/www.novelsmmigratom.tuiasi.ro\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=308"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}