摘要
铸造钛合金中存在八面体、棱面枝晶及光滑树枝晶等不同形态的TiC.本文结合定向凝固试样组织,用配位多面体理论分析了钛合金中TiC的生长基元及生长习性.认为TiC的配位多面体生长基元为六配位的TiC6,TiC6生长基元堆积时, {100}面族和{111}面族上的生长速率不同,容易形成以{111}面为显露面的八面体状TiC晶胚.TiC晶胚在熔体中生长时,在生长速率最快的<100>方向上生长出二次枝晶臂,并在生长过程中始终保持小面界面生长特征,最终形成棱面枝晶状TiC.如TiC晶体生长时生长速率慢的面族上形成大量的螺旋位错等缺陷,则棱面消失,形成树枝晶TiC.
The shape of TiC can be octahedral, facet or/and non-facet dendrite in as-cast Titanium alloys. The growth element and growth habit of TiC6 in titanium alloys were analyzed with the theory of coordination polyhedron through directionally solidified samples. The results indicate that the growth elements of TiC are TiC6 with six coordinations. During the stacking of TiC6 growth element, the growth rates of families {100} and {111} are different, which may easily result in potential. nuclei of octahedral TiC surrounded by {111}. During the growing of TiC in the melt, the undercooling and composition at different part of the crystal's surface vary significantly. Some quadratic dendrites may appear in the direction of <100> and are characterized by facet growth resulting in facet dendritic TiC finally. If a large amount of defects such as screw dislocation are formed on the slowly growing surface of TiC during the growth, the facet will disappear and non-facet dendritic TiC will form.
出处
《无机材料学报》
SCIE
EI
CAS
CSCD
北大核心
2004年第6期1249-1254,共6页
Journal of Inorganic Materials
基金
2003黑龙江省高等院校骨干教师创新能力资助计划项目
