摘要
为了探讨温度和应变率对NiTi记忆合金相变转换率的影响,本文利用准静态试验机和分离式Hopkinson压杆的恒应变率技术对板条状和圆柱状试样进行了不同应变率的试验,同时通过改变温度检查相变转换的速度,结果表明:在较低的10-2/s应变率下,NiTi记忆合金伪弹性变形过程自身就会有6.5℃温升,这意味着在高应变率下其性能是温度与率的耦合效应;随外界环境温度的增加,NiTi记忆合金的相变恢复速率由递增趋于一稳态值,当温度超过365K时,恢复速率趋缓至约0.014mm/s;随应变率增加,相变转换率会趋于极限,即应力诱发的奥氏体向马氏体相转化阶段在应变率超过6000/s时基本不变,表明更高的应变率已不能引起NiTi相变转换。
To explore the effect of temperature and strain rate on the phase-transformation velocity of NiTi shape-memory alloy（SMA）,different strain-rate tests of both plate-type and cylindrical samples were performed using a quasi-static testing machine and the split-Hopkinson pressure bar with a constant strain-rate technique,and at the same time the testing temperature were also changed to check the phase-transformation velocity of NiTi SMA.The results show that the temperature rises 6.5℃ during the pseudoelastic deformation process of the NiTi SMA under a lower strain rate of 10^-2/s,it means that a coupling effect of the temperature and strain rate will affect the properties of NiTi SMA under higher strain rates;the phase-transformation recovery velocity of NiTi SMA increases to a stable value with increasing surroundings temperatures.When the temperature is over 365K,the recovery velocity tends to 0.014mm/s;the phase-transformation velocity increases with increasing strain rate and to a limit when strain rate is higher than 6,000/s,it means that the stress-induced phase-transformation does not occur anymore,it also show that a higher strain rate has not induced the phase-transformation of NiTi SMA.
出处
《材料科学与工程学报》
CAS
CSCD
北大核心
2009年第5期735-739,共5页
Journal of Materials Science and Engineering
基金
陕西省科技攻关资助项目(2007K06-11)
