选区激光熔化成形Al-Ce-Sc-Zr合金的工艺优化与组织性能

Process optimization,microstructure and mechanical properties of Al-Ce-Sc-Zr alloy by selective laser melting

以气雾化Al-10Ce-0.4Sc-0.2Zr(质量分数)预合金粉末为原料,采用选区激光熔化(selective laser melting,SLM)法制备Al-Ce-Sc-Zr合金。通过光学显微镜和室温拉伸实验等研究激光功率和扫描速度对合金致密度与力学性能的影响,优化工艺参数;并采用X射线衍射仪、扫描电镜、透射电镜等研究最佳工艺参数下SLM成形的合金共晶组织形貌、物相组成和晶粒尺寸等。结果表明,激光功率和扫描速度跟合金致密度和力学性能之间呈非线性关系;随激光能量密度升高,合金致密度和力学性能先上升后下降。在激光功率为350 W、扫描速度为2000 mm/s的最优参数下成形的Al-Ce-Sc-Zr合金,致密度达到99.92%,抗拉强度和屈服强度分别为(441±3)MPa和(370±18)MPa,伸长率为(9.4±0.9)%。SLM成形Al-Ce-Sc-Zr合金具有柱状晶和等轴晶交替分布的晶粒组织,晶粒取向较随机,不存在明显的织构。合金由α-Al和Al_(11)Ce_(3)相组成,Sc、Zr原子主要以固溶的形式存在于α-Al中,共晶Al_(11)Ce_(3)相为不规则的条带状,平均宽度为35 nm,排列成不连续的复杂网络,共晶组织十分精细,且分布均匀。

Al-Ce-Sc-Zr alloy was performed by selective laser melting(SLM)using gas atomization Al-10Ce-0.4Sc-0.2Zr(mass fraction)pre-alloyed powders as raw materials.The effects of laser power and scanning speed on the relative density and mechanical properties of the alloy were studied by optical microscopy and room temperature tensile test to optimize the process parameters.X-ray diffractometer,scanning electron microscope and transmission electron microscope were also used to study the eutectic microstructure morphology,phase composition and grain size of the alloy prepared by SLM under the optimal process parameters.The results show that the relationship between laser power,scanning speed and the relative density,mechanical properties of the alloy are non-linear,with the increase of laser energy density,the relative density and mechanical properties of the alloy show a trend of increasing and then decreasing.The optimum parameters are laser power of 350 W and scanning speed of 2000 mm/s.The relative density of Al-Ce-Sc-Zr alloy after process optimization can reach 99.92%with tensile strength of(441±3)MPa,yield strength of(370±18)MPa and elongation of(9.4±0.9)%.The as-built Al-Ce-Sc-Zr alloy presents a columnar-equiaxed bimodal grain structure.The grain orientation is relatively random,indicating that no strong texture is formed.The alloy consists ofα-Al and Al_(11)Ce_(3) phases.Sc and Zr atoms are mainly presented as the form of solid solution inα-Al matrix.The eutectic Al_(11)Ce_(3) phase has an irregular ribbonlike morphology with an average width of 35 nm and is arranged in a complex discontinuous network.The eutectic microstructure is very fine and uniformly distributed.