Mg-1.9Zn-0.9Mn-xNd合金铸态组织与力学性能

Microstructure and mechanical properties of as-cast Mg-1.9Zn-0.9Mn-xNd magnesium alloys

利用光学显微镜、扫描电镜、X射线衍射分析仪、热/力模拟试验机、拉伸试验机等研究了Mg-1.9Zn-0.9Mn-xNd合金铸态组织与性能。结果表明：Mg-1.9Zn-0.9Mn合金组织为α-Mg＋α-Mn＋MgZn,当含钕量大于0.22 mass%时合金中出现了Mg-ZnNd三元合金相T1（六方晶格）和T2（斜方晶格）;随含钕量增加,三元合金相数量增大,屈服强度及显微硬度随之增加,但当三元合金相形态由不连续的块状向断网状和网状转变后,受力时晶间产生裂纹,使抗拉强度及断后伸长率降低;在热压缩试验中合金发生了不完全再结晶,钕使峰值应力从50.8 MPa提高到92.4 MPa,并且使动态再结晶晶粒细化。

Microstructure and mechanical properties of as-cast Mg-1.9Zn-0.9 Mn-xNd alloys were studied by means of optical microscope,scanning electron microscopy,X-ray diffraction,tensile tester and thermal/force simulator. The results show that the microstructure of the as-cast Mg-1.9Zn-0.9Mn alloy consists of α-Mg ＋ α-Mn ＋ Mg Zn phases,and the Mg-Zn-Nd ternary alloy phases T1 and T2 appear in the alloy when the content of Nd is higher than 0. 22 mass%. With the increase of Nd content,the amount of T1 and T2 phases increases,and the yield strength and micro-hardness of the as-cast alloys increase. However,the tensile strength and elongation of the as-cast alloy decrease due to the morphology of the ternary alloy phase changes from discontinuous bulk to fracture network or network. In addition,incomplete recrystallization of the alloy occurs during the thermal compression tests,the peak stress increases from 50. 8 MPa to 92. 4 MPa and the dynamic recrystallization grains are refined due to the Nd addition.