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采用激光熔覆Al-Si/Al_2O_3粉体来对Mg-Nd-Zn-Zr镁稀土合金进行表面改性,并对熔覆层的形貌、组织、相组成及性能进行了表征。X射线衍射(XRD)分析和扫描电镜(SEM)观察显示,熔覆层主要由α-Mg、Mg_2Si、Mg_(12)Nd以及Al_(3.21)Si_(0.47)或Mg_(17)Al_(12)几种相组成,而Al_2O_3则大部分聚集在熔覆层和基体之间的界面处。截面硬度测试显示,熔覆层的显微硬度最高值在3090至4750 MPa之间,是基体硬度(550 MPa)的5~8倍以上,这主要归结为熔覆层内晶粒细化、固溶强化、增强相的形成以及氧化物颗粒的弥散强化作用。在3.5%(质量分数)NaCl水溶液中的电化学测试显示,激光熔覆后的镁合金腐蚀电位上升,腐蚀电流密度可由基体的1.683×10~(-4)A/cm~2下降至激光熔覆后的0.843×10~(-5)A/cm~2,表明激光熔覆后样品表面的腐蚀性能也得到显著提高。
The laser cladding Al-Si / Al_2O_3 powder was used to modify the surface of Mg-Nd-Zn-Zr magnesium rare earth alloy. The morphology, microstructure, phase composition and properties of the coating were characterized. X-ray diffraction (XRD) and scanning electron microscopy (SEM) observations show that the cladding layer is mainly composed of α-Mg, Mg 2 Si, Mg 12 Nd and Al 3.21 Si 0.47 or Mg 17 Al 12. Several phases are formed, while most of Al 2 O 3 accumulates at the interface between the cladding and the matrix. Cross-section hardness tests show that the highest microhardness of the cladding layer is between 3090 and 4750 MPa, which is more than 5 times of the substrate hardness (550 MPa), which is mainly attributed to the grain refinement in the cladding layer Solution strengthening, enhancing phase formation and dispersion strengthening effect of oxide particles. The electrochemical tests showed that the corrosion potential of magnesium alloy after laser cladding increased and the corrosion current density decreased from 1.683 × 10 -4 (A / cm 2) to the laser melting After coating 0.843 × 10 -5 A / cm ~ 2, indicating that the surface of the laser cladding corrosion properties have also been significantly improved.