组织及相结构对Cu-Al-Be-B形状记忆合金阻尼与力学性能的影响

研究了Cu Al Be B形状记忆合金的成分、微观组织和相结构与阻尼和力学性能的关系 ,通过扫描电镜原位观察合金在单向拉伸应力作用下裂纹萌生和扩展的特征。结果表明 :应力诱发马氏体变体的转变使Cu Al Be B合金具有较高的阻尼性能 ;弹性各向异性和相变应变差引发晶界应力集中 ,导致合金在拉伸条件下发生晶间断裂 ;18R与 2H马氏体混合程度大时 ,会增加相变应变差引起的晶界应力集中和可能萌生的晶界裂纹源 ,大大减小合金的塑性和强度。

Effects of microstructure and phase structure on damping and mechanical properties of Cu-Al-Be-B shape memory alloys

The relationships between composition, microstructure and properties such as damping and mechanics as well as in situ extension of Cu-Al-Be-B shape memory alloys were investigated by means of SEM . It is showed that the high damping capacity of alloys ascribes to the stress induced interface motion of martensite variants. It is clear that microcracks nucleate and develop along polycrystalline boundaries, in which stress concentration resulted from elastic anisotropy and difference of phase transformation strain exist. The more the mixture of 18R and 2H martensites, the more the stress concentration and the probable cracks around polycrystalline borders, therefore weakening mechanical properties, namely resulting in low plasticity and tensile strength.