不同状态CuZnA(lRE)形状记忆合金热疲劳性能

Thermal Fatigue Properties of CuZnAl Shape Memory Alloy Under Different States

为了研究不同状态的CuZnA(lRE)形状记忆合金在冷热循环过程中的热疲劳性能及记忆效应的变化,将铸态、水淬+时效和油淬+时效的三种CuZnA(lRE)形状记忆合金在电阻炉加热自约束热疲劳试验机上进行试验,并结合金相、X射线衍射和电子显微镜分析,研究不同循环次数下合金的裂纹和显微组织变化。结果表明:随着循环次数的增加,三种状态的CuZnA(lRE)形状记忆合金裂纹的长大速率随着循环次数的增加先增大后减小,铸态合金裂纹增长速率最快,裂纹最长,热疲劳抗力最低;水淬+时效的试样裂纹和热疲劳性能居中;油淬+时效的CuZnA(lRE)形状记忆合金,裂纹最短,热疲劳性能最高;随着循环次数的增加,马氏体内的位错密度增加,有序度下降,记忆效应衰减。

In order to study thermal fatigue properties and memory effect change of CuZnAl （RE） shape memory alloy under different states in cold and heat cycle process, CuZnAl （RE） shape memory alloy specimens, respectively treated in the way of as-cast, water quenching＋aging and oil quenching＋aging, were researched in thermal fatigue testing machine of resistance furnace heating and self-constraint. By using metallograph, X-ray diffraction and electron microscope to analyze and research, alloy microcraek and microstructure change at different cycle times. The results show that with the increasing of cycle times, the growing rate of crack of the CuZnAl memory alloy under three states increased at first, then decreased. The crack growing rate of the as-cast alloy was the fastest and its crack was the longest. Thermal fatigue resistance of the as-cast alloy was the worst. CuZnAl（RE） shape memory alloy specimens, after the treatment of water quenching＋aging, the crack and thermal fatigue resistance were placed in the middle of the three states. After the treatment of oil quenching＋aging, the crack was the shortest and the thermal fatigue resistance was the best. With the increase of cycling times, dislocation density of martensite increased, the degree of order descended, and memory effect weakened.