抽拉速率对Ti-48Al-6Nb合金籽晶法定向凝固组织的影响  

Effects of Drawing Rate on Microstructure of Directionally Solidified Ti-48Al-6Nb Alloy with Seeding Technique

作　　者：周家东[1] 沈军[1] 杜玉俊[1] 熊义龙[1] 刘光振[1] 

机构地区：[1]西北工业大学凝固技术国家重点实验室,陕西西安710072

出　　处：《铸造技术》2014年第11期2625-2628,共4页Foundry Technology

基　　金：国家自然科学基金资助项目(51174167);凝固技术国家重点实验室自主研究课题资助项目(63-TP-2011)

摘　　要：以Ti-44Al-3Nb-2Si为籽晶,研究了不同抽拉速率对Ti-48Al-6Nb合金籽晶法定向全片层组织的影响。结果表明,6μm/s抽拉速率下,固/液界面为平界面生长,凝固组织中片层方向能够与生长方向保持一致。当抽拉速率增加到15μm/s时,固/液界面以枝晶方式生长,凝固组织中出现非择优<112軈0>取向的α相与择优取向β相共生生长组织。当抽拉速率增加到25μm/s时,α相树枝晶生长将在枝晶间析出β相,破坏定向全片层组织。用Ti-44Al-3Nb-2Si籽晶,低抽拉速率保证高温α相以平界面生长,可以实现Ti-48Al-6Nb合金的引晶。The effect of different drawing rates on directionally solidification fully lamellar microstructure of Ti-44Al-3Nb-2Si alloy with a polycrystalline seed was studied. The results show that, when the withdrawal rate is 6 μm/s,α-phase grow with planar/cellular morphology at unpreferred orientation, which make its lamellar microstructure parallel to the growth direction. Solid/liquid interface morphology begins to shift from cellular to dendritic when the withdrawal rate increases to 15 μm/s. There exists a couple growth of α phase with unpreferred growth direction of 〈1120〉 and β phase with preferred growth direction of 〈1120〉. When drawing rate growing to 25 μm/s,the seeding process easily failed because β phase formed in the interdendritic areas. Ti-48Al-6Nb can be seeded at a low drawing rate using Ti-44Al-3Nb-2Si seed, which made the α phase grown at planar.

关 键 词：Ti-44Al-3Nb-2Si籽晶 定向凝固 籽晶法 全片层组织 

分 类 号：TG146.23[一般工业技术—材料科学与工程]