热处理工艺对ZC63镁合金组织及性能的影响

利用光学显微镜、X射线衍射仪、扫描电镜和力学万能试验机等研究了ZC63镁合金在不同热处理工艺下的显微组织和力学性能的变化规律。结果表明:ZC63镁合金铸态组织主要由α-Mg和呈网状分布的CuMgZn相组成;经热处理后,强化相主要由颗粒状的CuMgZn和Mg2Zn3相组成。实验合金在445℃固溶24 h后,随着时效温度的升高,合金的抗拉强度和硬度值都逐渐降低,但在180℃时效20 h,伸长率最高,达到17.2%。热处理后合金的拉伸断口形貌中分布有颗粒状CuMgZn析出相,阻碍了晶界和位错的运动,裂纹沿着颗粒状析出相的边界以及内部扩展。

Effect of heat-treatment technology on microstructure and mechanical properties of ZC63 magnesium alloy

Microstructure and mechanical properties of ZC63 magnesium alloy under different heat-treated conditions were investigated by means of optical microscope(OM),X-Ray diffraction(XRD),scanning electron microscopy(SEM) and mechanical tests.Results show that the ZC63 magnesium alloy is composed mainly of α-Mg and bulky CuMgZn phase which is network-distributed on grain boundaries continuously.After heat-treatment,strengthening phases of granular CuMgZn and Mg2Zn3are observed in the alloy.After solid solution treatment at 445 ℃ for 24 h and then aging treatment,tensile strength and micro-hardness of the alloy reduce gradually with elevating aging temperature.However,when aging at 180 ℃ for 20 h,its elongation reaches the highest value of 17.2%.Some granular CuMgZn phases detected on the tensile fracture surface of ZC63 alloy after heat-treatment can hinder the movement of grain boundaries and dislocations,which enhances strength of the alloy and cracking occurs along the boundary and the interior of the granular precipitation phase.