凝固速度对金属基复合材料液固界面形态选择的影响

Affection of Solidification Rate on the Morphologies Shape of Liquidsolid Interface of Metal Matrix Composites

液固界面形态的转变决定着材料内部显微组织的变化，本文采用定向凝固的方法，研究了凝固速度对金属基复合材料液固界面形态选择的影响。随着凝固冷却速度的提高，Ａｌ２Ｏ３／Ａｌ４．５Ｃｕ复合材料液固界面形态将发生由胞状向树枝状的转变，其胞枝转变的临界速率实验值是４９．８μｍ／ｓ。当定向凝固Ａｌ２Ｏ３４．５Ｃｕ复合材料的液固界面形态为胞状界面时，界面对颗粒起推移作用；而当液固界面为枝晶形态时，颗粒被液固界面裹入。理论计算表明：颗粒被液固界面推移的临界速度为１２．４μｍ／ｓ，与实验值１６．７μｍ／ｓ处于同一数量级。

he transform of liquidsolid interface morphologies in the process of solidification affected the microstructure of materials,in the paper,using the directional solidified method was employed.The affection of solidification rate on the selection of liquidsolid interface morphologies of metal matrix composites have been researched.With the change of cooling rate,the shape of liquidsolid interface of Al2O3/Al4.5Cu composites was changed from cellslike to dendriteslike,an experimental value of the critical velocities of cellsdendrites transform was 49.8μm/s.While the shape of liquidsolid interface was as cellslike,particles were pushed by the liquidsolid interface;but as the shape of liquidsolid interface was as dendriteslike,particles ware entrapped.By the theoretical calculation,the numerical relation of critical velocities of particle pushed by the liquidsolid interface are 12.4μm/s,the theoretical calculation value are compared with the experimental value,they placed the same level.