树枝晶SiC_p/ZA27复合材料部分重熔过程中的组织演变  

Microstructural Evolution of Dendritic SiC_p/ZA27 Composite During Partial Remelting

作　　者：陈体军[1] 郝远[1] 马颖[1] 李庆林[1] 

机构地区：[1]甘肃工业大学材料科学与工程学院,甘肃兰州730050

出　　处：《铸造》2002年第12期741-744,共4页Foundry

基　　金：甘肃重点攻关项目 (GS992 A52 0 2 4 ) ;甘肃自然科学基金项目 (ZS0 1 1 A2 5 0 4 8 C)

摘　　要：用扫描电镜 (SEM )背散射成像技术对金属型铸造树枝晶SiCp/ZA2 7复合材料部分重熔过程中的组织变化进行了观察。结果表明 :在 460℃加热过程中 ,因晶界共晶组织向初生晶的扩散 ,造成树枝晶二次枝晶臂和晶粒间的快速合并 ,形成无明显晶界的组织 ,将分布于枝晶间的SiCp 裹入晶内 ,接着 ,剩余共晶组织开始熔化 ,组织发生分离 ,形成不规则的大块状组织 ,并将SiCp 返还于晶粒间的液相中 ,随后 ,因不规则组织突出部位 (曲率大 )的溶化 ,组织趋于圆整 ,最后经球状化形成尺寸较大的近球状颗粒。还从相变角度分析了组织的演变过程。The microstructural evolution of permanent mould casting dendritic SiC p/ZA27 composite during partial remelting was investigated using back scattered electron imaging technique in scanning electron microscopy (SEM). The results indicated that during the heating at 460℃, the matrix dendrites coarsened resulted from the merging of the secondary dendritic arms due to the dissolving of the inter dendritic eutectics into the primary grains and formed the structure with no obvious boundaries, in which the SiC p was entrapped. Subsequently, the residual eutectics began melting and thus the structure was separated into big irregular pieces, and the SiC p was returned to the liquid phase between the solid grains. Followed, the regular structures tended to become circumference due to the melting of their project regions (with high curvature), and finally, they evolved into large near globular solid grains through spheroidization. This structure evolution was also discussed through analyzing the phase transformations occurred during this process.

关 键 词：树枝状晶 SICP/ZA27复合材料 部分重熔 组织演变 触变成形 

分 类 号：TB333[一般工业技术—材料科学与工程] TG249.[金属学及工艺—铸造]