五瓣星状初晶硅形核机制  

NUCLEATING MECHANISM OF FIVE PETAL STAR-SHAPED PRIMARY SILICON

作　　者：桂满昌[1] 贾均[1] 李庆春[1] 

机构地区：[1]北京航空材料研究院,哈尔滨工业大学,北京航空材料研究院先进复合材料国防科技重点实验室

出　　处：《金属学报》1996年第11期1177-1183,共7页Acta Metallurgica Sinica

摘　　要：过共晶Ａｌ－Ｓｉ合金五瓣初晶硅具有简单多面体原子团簇凝并形核的特点，热力学分析表明，低温熔体中预存的四面体和八面体硅原子团簇以五重孪晶关系凝并是一自发过程．凝并后的多面体具有生长成五瓣星状初晶硅的内在条件．小于晶核临界尺寸的原子团簇凝并后可成为稳定的五瓣星状初晶硅生长的晶核．Five petal star-shaped primary silicon in hypereutectic Al-Si alloy possesses a nucleating characteristic by agglomerating from tiny polyhedron clasters with simple shape.From the veiwpoint of thermodynamics, it is a spontaneous process that the five fine tetrahedron or octahedron clasters agglomerate in a way of fivefold twinning. The agglomerated polyhedron may grow into a five petal star-shaped primary silicon. By combining clasters with smaller size than that of critical nucleation, the polyhedron can acts as a stable nucleus of primary silicon.

关 键 词：初晶硅 形核 凝并 铝硅合金 

分 类 号：TG146.21[一般工业技术—材料科学与工程]