Solidified Structure and Corrosion Behavior of Laser-melt Magnesium Alloy
FANG Zhi-hao1,2, MA Cheng-peng2, GUAN Ying-chun2,3,4,5, ZHOU Wei4, ZHENG Hong-yu5
1. School of Energy and Power Engineering, Beihang University, Beijing 100191, China;
2. School of Mechanical Engineering and Automation, Beihang University, Beijing 100191, China;
3. International Research Institute for Multidisciplinary Science, Beihang University, Beijing 100191, China;
4. School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798;
5. Singapore Institute of Manufacturing Technology, Singapore 638075
Abstract：The AZ91D magnesium alloy samples were scanned by millisecond pulse Nd:YAG laser under high pure argon protection. The surface morphology, microstructure and composition of the treated magnesium alloy were studied by X-ray diffraction, optical microscopy, scanning electron microscopy, atomic force microscopy. In addition, the corrosion surface which was corroded using simulated body fluid and the mass fraction of 3.5%NaCl solution was observed and material corrosion rate was calculated. The results show that, at the same corrosion time, compared with the untreated samples, the surface corrosion resistance is improved by the enrichment of Al at the irradiated surface by the joint effect of the combination of refined homogeneous microstructure of α-Mg phase and β-Mg17Al12 phase and the selective vaporization and the chemical composition of base metal in the laser-treated AZ91D alloy; the solidification equation is obtained by calculating the relation between the size of the dendrite cell and the cooling rate in laser melting zone.
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