【摘要】 为提高选区激光熔化(SLM)成形AlSi10Mg合金的疲劳性能,采用WC/AlSi10Mg复合材料粉末制备试样,采用OM和SEM观察了AlSi10Mg复合材料试样的微观组织,利用显微硬度计和高频疲劳实验机研究了AlSi10Mg复合材料试样的显微硬度和疲劳性能。结果表明:熔池内部及边缘不同的凝固条件使两处晶粒生长形态各不相同,熔池边界为胞状晶,内部为树状晶。熔池边界到内部分为粗晶区、热影响区、细晶区三个区域,对应的平均α-Al基体尺寸分别约为1.5μm、1.0μm、0.6μm,平均共晶Si宽度约0.5μm;对应的Al-Si共晶含量分别为(40±3)%、(37±4)%、(30±2)%,但均远小于室温下平衡态Al-Si相图中共晶组织的含量,大部分Si以过饱和形式固溶于Al基体中。纳米WC富集在晶界,且部分WC发生溶解扩散式烧损。疲劳实验结果表明,试样局部存在严重夹杂,使得疲劳裂纹源萌生于试样次表层;试样断口具有解理断裂特征,试样高周疲劳寿命服从三参数威布尔分布,据此建立了选区激光熔化AlSi10Mg复合材料试样的寿命预测模型。更多还原

【Abstract】 In order to improve the fatigue properties of the selected laser melting( SLM) forming AlSi10Mg alloy,a sample of AlSi10Mg composite containing nano-WC was obtained by selective laser melting forming technology. The microstructure of AlSi10Mg alloy sample was observed by OM and SEM. The microhardness and fatigue properties of AlSi10Mg alloy parts were studied by microhardness tester and high frequency fatigue tester. The results show that different solidification conditions in the inside and outside make the growth morphology of the two grains different. The boundary of the pool is cellular crystal and the interior is dendritic crystal. The molten pool is divided into three regions: coarse grain zone,heataffected zone and fine grain zone. The corresponding average α-Al matrix size is about 1. 5 μm,1 μm and 0. 6 μm,respectively,and the average eutectic Si width decreases in turn,about 0. 5 μm. The Al-Si eutectic content is( 40 ± 3) %,( 37 ± 4) %,( 30 ± 2) %,respectively,but both are smaller than the eutectic structure of the Al-Si phase diagram at equilibrium,and most of the Si is dissolved in supersaturated form. In the Al matrix. Nano WC is enriched in the grain boundary,and part of the WC undergoes dissolution diffusion burning. The fatigue test results show that the fracture of the specimens has cleavage fracture characteristics,and the fatigue crack originates in the sub-surface layer of the specimens due to the existence of serious inclusions. The high cycle fatigue life of the specimens obeys three-parameter Weibull distribution,and the life prediction model of 3 D printed specimens is established.更多还原