摘要
采用OM,EBSD,XRD,TEM和SQUID研究了3种不同Mn含量的固溶态Fe-（14~21）Mn-5.5Si-8.5Cr-5Ni合金在马氏体转变开始温度Ms以上10 K（Ms＋10 K）变形前后的形状记忆效应和微观组织.结果表明,固溶态Fe-（14~21）Mn-5.5Si-8.5Cr-5Ni合金的形状记忆效应随Mn含量增加而增加.这是由于：一方面,奥氏体屈服强度与应力诱发e马氏体临界应力的差值随着Mn含量的增加而增大,即提高Mn含量增强了奥氏体抵抗塑性变形的能力;另一方面,Mn含量的提高减小了应力诱发e马氏体的宽度,抑制了a’马氏体的引入,从而提高了应力诱发e马氏体的可逆性.
Fe-Mn-Si base shape memory alloys（SMAs）, as compared with Ni-Ti and Cu base SMAs, have attracted much attention since the 1980 s due to their promising advantages, such as low cost, good workability and weldability. However, the recovery strain of polycrystalline Fe-Mn-Si base SMAs is only about 2%~3% except single crystals and ribbons ones. At the present time, in order to enhance the recovery strain of this kind of alloys,some methods such as thermo-mechanical training, ausforming and thermo-mechanical treatment are used. In recent years, the research group had prepared training-free cast Fe-Mn-Si base alloys showing an excellent shape memory effect（SME）. Unfortunately, the grains of cast Fe-Mn-Si base alloys are coarse, certainly leading to low yield strength and recovery stress. Many factors affecting the shape memory effect, such as alloy elements, the amount of pre-strain, deformation temperatures, annealing treatments and the training, have been studied. However, there is a debate on the effect of Mn contents on the shape memory effect of Fe-Mn-Si base alloys. The aim of this work is to clarify the debate, shape memory effect and microstructures of solution treated Fe-（14~21）Mn-5.5Si-8.5Cr-5Ni alloys were investigated by OM, EBSD, XRD, TEM and SQUID before and after deformation at 10 K higher than their start temperature of martensitic transformation（Ms＋10 K）. The result showed that the shape memory effect of solution treated Fe-（14~21）Mn-5.5Si-8.5Cr-5Ni alloys increased with the Mn contents. There are two reasons for this result. One is that the difference value between austenitic yield strength and critical stress of stressinduced e martensite increased with the Mn contents. In other word, the ability resisting plastic deformation was improved by increasing the Mn contents. The other is that the reversibility of e martensite reverse transformation was enhanced by increasing the Mn contents because the width of stress-induced e martensite decreased while the a’ martensite was difficult to be introduced with increasing the Mn contents.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2015年第2期201-208,共8页
Acta Metallurgica Sinica
基金
国家自然科学基金项目51171123和51271128资助~~
