能量密度对激光选区熔化成形AlSi10Mg合金缺陷及力学性能的影响

分析了能量密度对激光选区熔化成形AlSi10Mg合金致密度的影响规律，并采用微纳CT检测结合EDS能谱分析的方法，统计了试样内部缺陷的类型和尺寸，分析了缺陷在试样三维层面上的分布规律及产生原因，得出了影响激光选区熔化成形AlSi10Mg合金致密度和内部缺陷的主要因素。结果表明，合适的激光能量输入是获得高致密度的关键，当激光能量密度处于47.62~50.00 J/mm³区间时，试样致密度最高，此时试样中夹杂缺陷消失，孔洞缺陷最大尺寸降至0.056 mm。孔洞缺陷产生原因主要与未熔粉体、空心粉及氧化物有关。在优选激光能量密度区间内成形的AlSi10Mg合金试样，其平均抗拉强度和伸长率分别在294 MPa和8.0%以上，优于铸造AlSi10Mg合金。

Effect of Energy Density on Defects and Mechanical Properties of AlSi10Mg Alloy Fabricated by Selective Laser Melting

The influence of energy density on relative density of the formed AlSi10Mg alloy is analyzed, and the types as well as sizes of internal defects in AlSi10Mg samples are counted by micro-nano CT detection together with energy dispersive spectrometer (EDS) analysis. The three-dimensional distribution and causes of defects with the samples are analyzed, and the main factors affecting the relative density as well as internal defects of selective laser melting fabricated AlSi10Mg alloy are put forward. It is shown that appropriate laser energy input is the key to obtain high density. When the laser energy density is in the range of 47.62-50.00 J/mm³, the samples have the highest density, the inclusion defects disappear and the maximum size of the hole defects reduce to 0.056 mm. The causes of hole defects are mainly related to unmelted powder, hollow powder and oxides. The average tensile strength and elongation of AlSi10Mg alloy fabricated under the optimum laser energy density range are above 294 MPa and 8.0%, respectively, which are higher than those of cast AlSi10Mg alloy.