Hyeon-Taek Son
,
Jae-Seol Lee
,
Ik-Hyun Oh
,
Chang-Seog Kang
材料科学技术（英文）
The aims of this study are to investigate the effects of Nd addition in the Mg-Al-Ca alloys on microstructure and mechanical properties. Microstructure of as-cast Mg-5Al-3Ca alloy containing Nd consists of α-Mg matrix, eutectic phase and Al-Nd rich intermetallic compound. As Nd addition was increased, α-Mg matrix morphology was changed from dendritic to equiaxed grains and average value of grain size was decreased. Nd addition to Mg-5Al-3Ca based alloys resulted in the formation of Al-Nd rich intermetallic compounds at grain boundary and α-Mg matrix grains. And these Al-Nd rich intermetallic compounds were dispersed homogeneously. In these alloys, two kinds of eutectic phases were observed, i.e. coarse irregular-shape structure at grain boundary and fine needle-shape structure in the α-Mg matrix grain. It is found that the ultimate strength showed the maximum value of 271 MPa at Mg-5Al-3Ca-2Nd alloy and elongation was decreased as the addition of Nd was increased.
关键词:
Mg-Al-Ca alloy
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金属学报(英文版)
Macro-texture of an Mg-Al-Ca alloy prepared by friction stir welding (FSW) was investigated through pole figure measurement and X-ray diffraction (XRD) pattern analysis. It was found that at the top and bottom surfaces of friction stir zone (FSZ), (0002) basal planes of magnesium tend to be arranged parallel to the plate surface. In the cross section of FSZ, no obvious texture had evolved and (0002) basal planes showed a random distribution.
关键词:
friction stir welding (FSW)
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王峰
,
董海阔
,
王志
,
毛萍莉
,
刘正
金属学报
doi:10.11900/0412.1961.2016.00353
在浇注温度700 ℃、模具温度200 ℃条件下,通过热裂曲线和凝固曲线测试以及OM、XRD、SEM等手段分析了Ca加入量对Mg-5Al-xCa (x=0.5、1.0、2.0、3.0、4.0、5.0,质量分数,%)合金热裂敏感性的影响。结果表明,当Ca加入量增加到4.0%时,合金的热裂敏感性随着Ca加入量的增加而减小;Mg-5Al-4.0Ca合金的热裂敏感性最小,其热裂敏感性系数仅为0.824;Ca加入量增加到5.0%时,合金的热裂敏感性又出现上升,其热裂敏感性系数上升到0.96。加入适量的Ca会降低Mg-5Al-xCa合金凝固时α-Mg的析出温度,并抑制Mg17Al12相形成,缩小合金凝固温度范围,增加组织中的共晶含量,有利于合金凝固后期的补缩,从而降低合金的热裂敏感性。但加入过多的Ca会增加含Ca脆性相的数量,并使合金组织发生粗化,从而导致合金的热裂敏感性增加。
关键词:
Mg-Al-Ca合金
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热裂敏感性
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凝固曲线
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显微组织
