母相区时效和热循环对Cu－Zn－Al合金形状记忆特性的影响

Effects of Parent Phase Aging and Thermal Cycling on Shape Memory Characteristics in a Cu-Zn-Al Alloy

采用一种精确测量形状记忆效应（ＳＭＥ）的方法研究了Ｃｕ－２６％Ｚｎ－４％Ａｌ合金８００℃淬火后在母相区１３０，１５０和１７０℃时效以及相变热循环过程ＳＭＥ变化的规律。淬火马氏体进入母相区时效初期回复率迅速升高，达到一个最大值以后随时间开始下降，显示出时效过程中马氏体稳定化效应的消除和贝氏体相变发展这两种机制所引起的相反效果。拘束条件下热循环引起回复率的衰减比起自由状态下要缓慢。这可能是应力的存在有利于诱发马氏体相变，使马氏体回复率显著提高所致。

Changes in shape Memory effect(SME) during aging at 130,150 and 170℃ for theparent phase and thermal cycling in a Cu-26%(wt )Zn-4%(wt)Al alloy quenched from 800℃ werestudied by an exact measurement of SME, The shapememory recovery rate remarkably increases at theearly aging stage,during that time the quenchedmartensite transfOrms to the parent phase. However,after reaching a maximum value of theSME,it decreases with the aging duration. Thesefacts indicate that two opposite effects exist withboth different mechanisms between annihilation ofmatensite stabilization and bainite transhrmation. The declination of recovery rate produced from thethermal cycling on bending condition is more smooththan that on free condition. This phenomenon can beconsidered as that the existing stress is advantageousto induce the martensitic transformation leading toremarkablely increase the recovery rate ofmartensite.