离心转速对Mg-6Al-1Ca-1Nd合金组织和性能的影响

Effect of Centrifugal Speed on Microstructure and Properties of Mg-6Al-1Ca-1Nd Alloy

以Mg-6Al-1Ca-1Nd合金为研究对象,通过重力铸造和离心铸造制备出Mg-6Al-1Ca-1Nd合金试样,运用光学金相分析(OM)、扫描电子显微分析(SEM)、X射线衍射分析(XRD)、硬度测试等多种分析和测试手段,系统研究了重力铸造和离心转速对Mg-6Al-1Ca-1Nd合金组织及力学性能的影响。结果表明,与重力铸造试样相比,离心铸造Mg-6Al-1Ca-1Nd镁合金的晶粒得到了显著的细化,并且离心铸造试样为等轴晶。随着离心转速增加,合金的晶粒尺寸减小。XRD分析表明,离心铸造镁合金试样的中间相为Mg17Al12、Al2Nd和Al2Ca;而重力铸造试样中没有发现Al2Ca相的衍射峰,Mg17Al12和Al2Nd的衍射峰比较弱。硬度随离心转速增加而持续增加,离心速度为1541r/min时,硬度(HV)达到最大,为58.5。

The Mg-6Al-1Ca-1Nd alloy samples were fabricated by centrifugal casting method and by gravity casting,respectively.The microstructure and mechanical properties of Mg-6Al-1Ca-1Nd alloy fabricated were characterized by OM（optical microscope）,SEM（scanning electron microscope）,XRD（X-ray diffraction） and hardness testing.The results show that the grain size of Mg-6Al-1Ca-1Nd alloy exhibiting equaixed grain fabricated by centrifugal casting is finer than that fabricated by gravity casting.With increasing in centrifugal speed,the grain size is decreased.The XRD analysis shows that there exists Mg17Al12、Al2Nd and Al2Ca phases and α-Mg in the Mg-6Al-1Ca-1Nd alloy fabricated by centrifugal casting.However,absence of Al2Ca phase can be observed,and the content of Mg17Al12 and Al2Nd is decreased in the Mg-6Al-1Ca-1Nd alloy fabricated by gravity casting.With increasing in centrifugal speed,the hardness value of the alloy fabricated by centrifugal casting is increased,and with the centrifugal speed of 1 541 r/min,the hardness value reaches HV58.5.