选区激光熔化成形AlSi10Mg合金组织研究

Research on Microstructure of AlSi10Mg Alloy Fabricated by Selective Laser Melting

采用选区激光熔化成形方法制备了AlSi10Mg合金,并对其内部组织进行了分析.结果表明:AlSi10Mg合金横截面激光熔道呈长条状,熔池区内为细小弥散分布的胞状晶,熔池区边缘主要为尺寸较大的胞状晶.AlSi10Mg合金纵截面呈鱼鳞状,熔池区内主要为柱状晶,熔池区边界主要为胞状枝晶.熔道搭接区主要为取向不一致的粗大胞状枝晶.产生上述现象主要是由于熔池区内温度梯度小,溶质分布均匀,且过冷度较大,利于形成取向相同且细小的晶粒.在熔池区边界,后续熔化的熔池对已凝固的合金进行重熔,使已凝固区合金再结晶并长大,形成尺寸较大的晶粒.熔道搭接区不同熔池内热传递方向不同,且晶粒具有外延生长的特性,在搭接区形成取向各异的胞状枝晶.

The microtructure of AlSi10Mg alloy fabricated by selective laser melting was investigated.The results show that the morphology of laser scan line of AlSi10Mg alloy cross section is long strip.The refined cellular grain is dispersing in melt pool area.The boundary of the melt pool area is mainly large size cellular grain.The longitudinal section of AlSi10Mg alloy appears as a scale.The main grain of the melt pool area is columnar grain,and the boundary of the melt pool area is mainly cellular dendrite.The overlap area is mainly coarse cellular dendrite whose orientation is obviously different.The above phenomenon is mainly due to the small temperature gradient and homogeneous solute distribution in the melt pool area,and the supercooling is greater,thus forming the same orientation and fine grain.In the melt pool boundary,the previous solidified alloy is re-melted by subsequent melt pool,which causes the solidified alloy recrystallized and grow to form larger size grain.In the overlap area,the different direction of the heat transfer of the different melt pools and the epitaxial growth of grain,which causes the formation of cellular dendrites with different orientations.