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采用扫描电镜、室温和高温压缩实验等方法研究了Ni/Ti值对Ni42+xTi50-xAl4Hf4(x=0～7)合金的微观组织和力学性能的影响.Ni42+xTi50-xAl4Hf4合金由NiTi基体和Ti2Ni相组成,随着Ni/Ti原子数比值的增加,Ti2Ni相的尺寸和数量急剧减少,析出强化效果减弱.室温时,随着Ni/Ti值的增加,NiTiAlHf合金的压缩屈服强度和显微硬度逐渐降低,塑性提高.高温下,当Ni/Ti<1时,Ti2Ni相的析出强化起主要作用,合金的屈服强度随Ni/Ti值增加而降低;当Ni/Ti>1时,Hf固溶强化作用的影响提高,并且Ti2Ni相趋于均匀弥散分布,使合金的屈服强度随Ni/Ti值增加而升高.在化学计量比(Ni/Ti=1)两侧,合金的屈服强度变化不对称.
The effects of Ni / Ti value on the microstructure and mechanical properties of Ni42 + xTi50-xAl4Hf4 (x = 0 ~ 7) alloys were studied by means of scanning electron microscopy, room temperature and high temperature compression experiments.The Ni42 + xTi50-xAl4Hf4 alloy consists of NiTi matrix and Ti2Ni phase, with the increase of Ni / Ti atomic ratio, the size and amount of Ti2Ni phase decrease sharply, and the precipitation strengthening effect is weakened.The compressive yield strength and microstructure of NiTiAlHf alloy with the increase of Ni / Ti value at room temperature The hardness decreases and the plasticity increases.The precipitation strengthening of Ti2Ni phase plays a major role when the Ni / Ti <1 at high temperature, and the yield strength of the alloy decreases with increasing Ni / Ti value. When Ni / Ti> 1, Ti2Ni phase tends to be uniformly dispersed, and the yield strength of the alloy increases with the increase of Ni / Ti value. On both sides of the stoichiometric ratio (Ni / Ti = 1), the yield strength of the alloy Asymmetric.