摘要
以Ti-43Al-3Si为籽晶,研究了不同抽拉速率对TiAl合金耔晶法定向凝固全片层组织的影响．结果表明．60 mm／h抽拉速率下．凝固组织中的片层方向能够与生长方向保持一致．随抽拉速率增加,由于温度梯度降低、成分过冷增大等因素的影响,凝固组织中出现了与生长方向成45°或90°夹角的片层取向．电磁搅拌引起的强制对流使固／液界面前沿的扰动不断增强,晶体生长形态发生变化,破坏了片层取向的一致性．
Directional solidification （DS） of Ti-43Al-3Si alloy with a polycrystalline seed has been studied under the conditions of different growth rates. DS ingots with fully lamellar microstructure parallel to longitudinal axis （DS direction） were successfully obtained at a low growth rate of 60 mm/h. Increasing further the growth rate, the orientation of lamellar microstructure was no longer parallel to the DS direction and an angle of about 45° or 90° appeared between lamellar orientation and DS direction because of the variations of constitutional undercooling and temperature gradient. The distance between the transition point and the seed decreased with the increase of growth rate. Experiments also showed that the seeding process easily failed if the convection caused by electromagnetic stir was strong enough.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2006年第12期1238-1242,共5页
Acta Metallurgica Sinica
基金
国家自然科学基金资助项目50474054~~
关键词
TIAL
定向凝固
抽拉速率
籽晶法
TiAl, directional solidification, growth rate, seed technique
