Microstructure evolution and nitrides precipitation in in-situ Ti_2 AlN/TiAl composites during isothermal aging at 900°C  

原位合成Ti_2 AlN/TiAl复合材料900°C时效过程中的组织演化及氮化物沉淀相析出(英文)

作　　者：刘懿文[1] 胡锐[1] 张铁邦[1] 寇宏超[1] 李金山[1] 

机构地区：[1]西北工业大学凝固技术国家重点实验室,西安710072

出　　处：《Transactions of Nonferrous Metals Society of China》2014年第5期1372-1378,共7页中国有色金属学报（英文版）

基　　金：Project(2011CB605502)supported by the National Basic Research Program of China;Project(51001086)supported by the National Natural Science Foundation of China

摘　　要：Microstructures of Ti2AlN/TiAl composites prepared by in-situ method were characterized in in-situ and aging treatment conditions and the nitride precipitation was investigated in Ti2AlN/TiAl composites aged at 900 ℃ for 24 h after being heat treated at 1400 ℃ for 0.5 h. The in-situ composites consist of γ＋α2 lamellar colonies, equiaxed y grains and Ti2AlN reinforcements. Matrix with nearly fully lamellar structure formed after solution and subsequently aging treatment. With the increase of Ti2AlN content, the nearly fully lamellar structure becomes instable for the aged composites. According to TEM study, fine Ti2AlN precipitates are found to distribute at the grain boundaries of lamellar colony. Needle-like Ti3AlN precipitates arrange in line with growing axis parallel to [001] direction of the γ-TiAl matrix and another needle-like Ti3AlN precipitates with lager size distribute at the dislocations. Key words：对原位合成Ti2AlN/TiAl复合材料在原位合成及时效热处理条件下的显微组织特征进行分析,并对Ti2AlN/TiAl复合材料进行1400°C,0.5 h固溶及900°C,24 h时效热处理,研究其氮化物沉淀析出。结果表明,原位合成复合材料的显微组织由γ+α2片层团、等轴γ晶粒和Ti2AlN增强相组成。经固溶和时效处理后,获得近全片层基体结构。随着Ti2AlN含量的增加,基体近全片层结构变得不稳定。对时效后的复合材料进行TEM研究,发现在片层团晶粒边界上分布着细小的Ti2AlN沉淀相。在γ-TiAl基体内,针状Ti3AlN沉淀相以其轴向平行于基体[001]方向排列,而另一种具有较大尺寸的Ti3AlN沉淀相则在位错处沉淀析出。

关 键 词：TiAl composites Ti2AlN in-situ synthesis microstructure PRECIPITATES aging treatment 

分 类 号：TB331[一般工业技术—材料科学与工程] TG156.92[金属学及工艺—热处理]