Mg-6.4La-4.87Al镁合金的金属型和压铸组织与性能

Microstructure and Properties of Metal Mold and Die Cast Mg-6.4La-4.87Al Magnesium Alloy

制备铸态与压铸态Mg-6.48La4.87Ar两种合金试样,采用OM、SEM和XRD分析其微观组织和相组成,并测试室温拉伸与压缩力学性能、导热性能和流动性能。结果表明:铸态晶粒粗大,第二相分布不均匀;经传统压铸后,晶粒变得细小,第二相分布均匀。两者试样微观组织均主要由a-Mg基体、点状Al_(11)La_(3)相和少量针状Mg_(12)La相组成。铸态试样抗拉强度、抗压强度和伸长率分别为157MPa、263MPa和4.0%,经压铸后试样抗拉强度、抗压强度和伸长率分别提高至236MPa、345MPa和4.5%,较铸态值分别提高63%、31%和13%,同时呈现较好的流动性能,流动长度为1374mm。铸态试样导热系数达到113.2W/(m·K),经压铸后仍能保持较高的导热系数,为90.9W/(m·K)。

The as-cast and die-cast Mg-6.48La-4.87Al alloy samples were prepared.The microstructure and phasecomposition of the as-cast and die-cast Mg-6.48La-4.87Al alloy samples were analyzed by OM,SEM and XRD,and themechanical properties,thermal conductivity and flow properties of the as-cast and die-cast Mg-6.48La-4.87Al alloy sampleswere tested at room temperature.The results show that the as-cast grain is coarse and the distribution of the second phase is notuniform After traditional die-casting,the grains become fine and the second phase is evenly distributed.The microstructureof both samples is mainly composed of a-Mg matrix,punctate Al_(11)La_(3) phase and a small amount of acicular Mg_(12)La phase.The tensile strength,compressive strength and elongation of the as-cast samples are 157 MPa,263 MPa and 4.0%,respectively.After die-casting,the tensile strength,compressive strength and elongation of the as-cast samples are increasedto 236 MPa,345 MPa and 4.5%,respectively,which are 63%,31%and 13%higher than the as-cast values,respectively.At the same time,they show good flow performance.The flow length is 1374 mm.The thermal conductivity of the as-castsample reaches 113.2 W/(m·K),and it can still maintain a high thermal conductivity of 90.9 W/(m·K)after die-casting.。