一种奥氏体铁镍基合金中的锯齿流变现象  

SERRATED FLOW IN A FeNi-BASED AUSTENITIC ALLOY

作　　者：赵帅[1] 李秀艳[1] 戎利建[1] 

机构地区：[1]中国科学院金属研究所,沈阳110016

出　　处：《金属学报》2011年第8期1017-1021,共5页Acta Metallurgica Sinica

基　　金：国家自然科学基金资助项目50601028~~

摘　　要：采用3种应变速率在不同温度下对一种奥氏体铁镍基合金进行拉伸实验,结果发现在300—700℃范围内发生锯齿流变现象;锯齿流变现象在300—600℃范围内表现为凸起式锯齿,而在700℃时表现为下凹式锯齿;此锯齿流变具有热激活性,即较高的拉伸温度使锯齿易于发生,较大的拉伸速率则抑制其发生.对比分析室温(不发生锯齿流变)及400℃(显著发生锯齿流变)拉伸试样的微观组织,发现在400℃拉伸后的孪晶界上存在明显的位错塞积,说明孪晶界可以有效地阻碍滑移变形,引起孪晶界附近应力积累,从而导致了凸起式锯齿流变的发生.孪晶界数量对锯齿波形的影响证实了此观点.Tensile tests on a FeNi-base austenitic alloy,with different amount of twin boundaries, were conducted at different temperatures and three strain rates,respectively.The results show that serrated flow occurs at temperatures from 300 to 700℃.This serrated flow exhibits bulge-like serrations at temperatures from 300 to 600℃and stress-loss serrations at 700℃ which manifests the nature of thermal activation,i.e.higher temperatures boost serrations and higher strain rates depress them.Investigations on samples deformed at room temperature（no serrated flow） and 400℃ prominent serrated flow） indicate that twin boundaries are strong enough to block slip deformation at 400℃.As a result,stress accumulates on twin boundaries and bulge-like serrations appear on the tensile curves.Effect of twin boundary amount on the morphologies of serrations testified this mechanism.

关 键 词：锯齿流变 铁镍基合金 孪晶界 位错 滑移变形 

分 类 号：TG142.25[一般工业技术—材料科学与工程]