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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,α-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α-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。
The rare earth Pr was used to modify the highly wear-resistant hypereutectic Al-16% Si alloy. The microstructure of the alloy was observed with a metallurgical microscope. The effect of technological parameters on the microstructure of the alloy was investigated. The results show that rare earth Pr can inhibit the generation of large undercooling by adsorbing on the front of the crystalline phase of silicon, and has obvious degenerative effect on primary and eutectic silicon. As the content of rare earth increases, coarse primary silicon becomes fine lath, eutectic silicon changes from needle to sphere, and α-Al changes from dendritic to spherical. With the increase of metamorphic time , The lath primary silicon becomes smaller and smaller, the size of eutectic silicon decreases slowly first and then increases gradually, and the metamorphic effect of rare earth on α-Al weakens; with the increase of metamorphic temperature, rare earth On the primary silicon metamorphism strengthened, while the eutectic silicon metamorphism weakened.