稀土Pr对Al-16%Si组织的影响
Influence of Rare Earth Pr on Microstructure of Al-16%Si Alloy
张 坚， 赵龙志， 赵明娟， 熊光耀
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作者单位：（华东交通大学 载运工具与装备省部共建教育部重点实验室，江西 南昌 330013）
中文关键字：稀土Pr；过共晶Al-Si合金；工艺参数；变质机理
英文关键字： rare earth Pr; hypereutectic Al-Si alloy; process parameters; modifying mechanism
中文摘要：采用稀土Pr对高耐磨过共晶Al-16%Si合金进行变质处理，运用金相显微镜观察合金的组织形貌，研究工艺参数对合金微观结构的影响，提出了稀土Pr的变质机理。结果表明：稀土Pr通过吸附在硅相结晶前沿，抑制了较大过冷度的产生，对初晶硅和共晶硅具有明显的变质效果。随着稀土含量的增加，粗大的初晶硅变成了细小的板条状，共晶硅从针片状变成了球状，?琢-Al从树枝状变成了球状；随着变质时间的延长，板条状初晶硅变得越来越细小，共晶硅的尺寸先是慢慢减小，然后又逐渐增大， 稀土对?琢-Al的变质效果减弱；随着变质温度的升高，稀土对初晶硅的变质作用加强，而对共晶硅的变质作用减弱。
英文摘要：The modification of rare earth Pr on high wear resistance hypereutectic Al-16%Si alloy was investigated by optical metallurgical microscope， the influence of process parameters on the microstructure was analyzed and the modification mechanism of rare earth Pr was put forward. The results show that the rare earth Pr absorbed on Si phase crystal frontier restrains the presence of large super cooling degree, which boosts the modification of rare earth Pr on silicon phase. With the increase of rare earth Pr content, the size of primary silicon phase is becoming smaller and smaller and the shape of the eutectic Si and ?琢-Al is changed into small circle. With the increase of modifying time, the primary Si becomes small and narrow, but the size of eutectic silicon first decreases and then increases. With the increase of modifying temperature, the modification of rare earth Pr enhances on primary silicon, fades on eutectic silicon.