Xuexi ZHANG
,
Dezun WANG
,
Dongyan DING
,
Congkai YAO
材料科学技术（英）
Mathematical model of unidirectional infiltration was set up and metal infiltration velocity and temperature fields of the metal, preform, and composites were calculated using the finite difference method. The metal infiltration velocity has a close relationship with infiltration time. It is very large after the infiltration begins in a few seconds, then the velocity keeps almost constant. The temperature field of the composite proves that metal matrix composites (MMCs) after unidirectional pressure infiltration can solidify from the entrance of the preform to the infiltration front, which is useful for obtaining the MMCs with low porosity and high properties.
关键词:
Wenlong ZHANG
,
Dezun WANG
,
Zhongkai YAO
,
Mingyuan GU
材料科学技术（英）
A 15 vol. pct SiCCw/Al composite was fabricated by a squeeze cast route followed by hot extrusion in the extrusion ratio of 18:1 and cold rolling to 50%. Microstructural evolution in the cold rolled composite during annealing was studied using macrohardness measurement and transmission electron microscopy (TEM). It was found that, during cold rolling the plastic flow of the matrix was restricted by the whiskers around them along the rolling direction, which resulted in different microstructure from near whiskers to far away. The cold rolled composite exhibited different microstructural development on 1 h annealing at different temperatures. Under annealing at about 100℃, recovery reaction occurred obviously and the introduction of SiC whiskers resulted in enhanced recovery reaction. Under annealing above about 200℃, recrystallization (growth of nuclei by high-angle grain boundary migration) and extended recovery took place simultaneously. When annealing temperature was increased up to 500℃, recrystallization fully took place in the cold rolled microstructure. The starting temperature of recrystallization was about 200℃. Whiskers played a role in stimulating the nucleation of recrystallization.
关键词:
Metal matrix composites
,
null
,
null
