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张志民,张可敏,邹建新,刁云华.Mg-Nd-Zn-Zr合金表面激光熔覆Al-Si/Al2O3复合涂层研究[J].稀有金属材料与工程(英文),2017,46(9):2594~2600.[Zhimin Zhang,Kemin Zhang,Jianxin Zou,Yunhua Diao.Study on laser cladding of a Mg-Nd-Zn-Zr Mg alloy with Al-Si/Al2O3 powders[J].Rare Metal Materials and Engineering,2017,46(9):2594~2600.]
Study on laser cladding of a Mg-Nd-Zn-Zr Mg alloy with Al-Si/Al2O3 powders
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Received:May 17, 2015  Revised:August 02, 2015
DOI:
Key words: laser cladding  Mg-Nd-Zn-Zr alloy  composite coating  micro-hardness  corrosion property
Foundation item:国家自然科学基金资助(项目号51271121,51471109)
Author NameAffiliationE-mail
Zhimin Zhang School of Materials Engineering,Shanghai University of Engineering Science 360357418@qq.com 
Kemin Zhang School of Materials Engineering,Shanghai University of Engineering Science zhangkm@sues.edu.cn 
Jianxin Zou National Engineering Research Center of Light Alloy Net Forming,Shanghai Jiao Tong University  
Yunhua Diao School of Materials Engineering,Shanghai University of Engineering Science  
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Abstract:
      In this paper, laser cladding of Al-Si/Al2O3 powders was applied on a Mg-Nd-Zn-Zr magnesium rare earth alloy, and the microstructure, phase components and properties of the clad layers were carefully characterized. X ray diffraction (XRD) analyses and scanning electron microscope (SEM) observations show that the clad layer is mainly consisted of α-Mg, Mg2Si, Mg12Nd and Al3.21Si0.47 or Mg17Al12 phases. However, Al2O3 particles agglomerate at the bottom of the clad layer close to the melt-substrate interface. The cross section microhardness tests reveal that the maximum hardness of the clad layer ranges from 309HV to 475HV, about 5 to 8 times higher than that of the Mg-Nd-Zn-Zr alloy (55HV) substrate. Such an increased hardness is attributed to the grain refinement, the solution strengthening, the formation of hardening phases and the dispersion strengthening from oxide particles. According to the potentiodynamic polarization measurements carried out in the 3.5wt% NaCl water solution, the corrosion potential of the alloy increased after laser cladding, while the corrosion current density decreased from 1.683×10-4(A/cm2)for the Mg alloy substrate to 0.843×10-5(A/cm2)for the laser clad alloy. Therefore, the corrosion resistance of Mg-Nd-Zn-Zr alloy can also be significantly improved by laser cladding with Al-Si/Al2O3 powders.