摘要
以Ti-43Al-3Si为籽晶,在Ti-47Al合金中成功的制备出了与生长方向平行的定向全片层组织.结合Ti-Al二元相图,分析了亚包晶和过包晶成分合金的凝固路径,确定了籽晶法控制TiAl合金片层方向对母料合金成分的要求.通过对不同生长速率下Ti-47Al合金籽晶法定向凝固组织的观察发现,成功的引晶生长应保证高温α相沿非择优取向〈11■0〉以平界面生长,即采用足够高的温度梯度和足够低的生长速率.α相胞状树枝晶生长过程中将在枝晶间析出β相,破坏定向全片层组织.
By using a seed crystal, the TiAl/Ti3Al lamellar orientation was aligned parallel to the growth direction in directionally solidified Ti-47Al alloys. The solidification behaviors of hypo-peritectic and hyper-peritectic alloys in Ti-Al equilibrium phase diagram were studied, and the composition range of successful seeding of TiA1 alloys was also determined. Through the lamellar microstructure examination of Ti-47Al alloys directionally solidified from Ti-43Al-3Si seed under the conditions of different growth rates, it was found that a successful seeding requires the solid/liquid interface must be plane during solidification. This can be achieved by growing crystals at a sufficiently high thermal gradient in the liquid and at a sufficiently low growth rate, which made the α phase grown along unpreferred growth orientation of 〈11^-20〉. The seeding process easily failed if β phases preaipitated between the α dendrites, which made the lamellax direction change.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2007年第12期1287-1292,共6页
Acta Metallurgica Sinica
基金
国家自然科学基金50474054~~
关键词
TIAL
定向凝固
全片层组织
籽晶法
TiAl, directional solidification, fully lamellar structure, seed technique
