Fe-Ni机械合金化过程中马氏体的形成及相变

研究了Ni含量、机械合金化工艺参数对Fe-Ni机械合金化过程中马氏体相变的影响及其机理.结果表明:在Fe-Ni机械合金化过程中存在着马氏体相变,但继续机械合金化马氏体是否会发生逆转变主要由Ni含量决定.当Ni≤30%(质量分数,下同)时,机械合金化引起的材料局部温度未达到形变促使马氏体相变逆转变开始温度,因此继续机械合金化马氏体不转变.对于Fe-35Ni,形变促使逆转变的开始温度低于局部温升,马氏体将向奥氏体转变.当Ni含量为35%时,随着机械合金化时间的延长、球磨速度和球料比的提高,机械合金化可以提供的相变驱动力增大导致奥氏体的量逐渐增多.

Martensite formation during mechanical alloying of Fe--Ni and martensitic transformation

Effects of nickel content and mechanical alloying parameters on martensitic transformation during mechanical alloying of Fe-Ni as well as the mechanism were studied. There exists martensitic transformation during mechanical alloying of Fe-Ni, but whether reverse transformation takes place with further mechanical alloying depends on the nickel content. For nickel content less than 30%(mass fraction), the highest temperature due to mechanical alloying is not high enough to reach the temperature at which strain-induced transformation of martensite to austenite starts, therefore martensite remains. However, further mechanical alloying of Fe-35Ni results in the transformation of martensite to austenite because strain-induced transformation temperature is lower. During mechanical alloying of Fe-35Ni, austenitic volume fraction increases with the increase of milling time, planetary rotation speed and the mass ratio of ball-to-powder because more energy can be provided for phase transformation.