论文部分内容阅读
为提高镁合金的表面硬度,对预置Si粉的AZ91D进行高能CO2激光表面改性处理。采用光学显微镜、扫描电镜、电子探针微区分析和X射线衍射仪等方法研究了激光改性层的组织结构。结果表明:AZ91D表面改性层主要由α-Mg,Al12Mg17和Mg2Si组成。Si粉与镁合金完全发生反应形成金属间化合物Mg2Si,Mg2Si以树枝状分布。Al-Mn相由AZ91D基体中的团聚棒状变为激光改性层中的分散球状。激光表面改性后,由于Mg2Si相产生的强化和Mg17Al12产生的细晶强化,显微硬度从80HV提高到324HV。
In order to improve the surface hardness of magnesium alloy, high-energy CO2 laser surface modification was performed on AZ91D with Si powder. The microstructure of the laser-modified layer was studied by optical microscopy, scanning electron microscopy, electron probe microanalysis and X-ray diffraction. The results show that the AZ91D surface modification layer mainly consists of α-Mg, Al12Mg17 and Mg2Si. Si powder completely reacts with the magnesium alloy to form intermetallic compound Mg2Si, which is distributed in a dendritic shape. The Al-Mn phase is changed from agglomerated rods in the AZ91D matrix to dispersed spheres in the laser-modified layer. After laser surface modification, the microhardness increases from 80HV to 324HV due to the strengthening produced by Mg2Si phase and the fine grain strengthening by Mg17Al12.