铸造TiAl合金定向层片组织持久性能的试验研究  

Creep Rupture Properties of Preferred Orientation Lamellar Microstructure of Cast TiAl Alloys

作　　者：骆晨[1] 朱春雷[1] 李海昭[1] 柳学全[1] 

机构地区：[1]钢铁研究总院高温材料研究所,北京100081

出　　处：《稀有金属》2012年第5期700-705,共6页Chinese Journal of Rare Metals

基　　金：国家科技部973计划资助项目(2011CB605503)

摘　　要：评价了铸造Ti-47.5Al-2.5V-1.0Cr合金定向层片组织在(750～800)℃/(220～350)MPa不同条件下的持久性能,并分别探索了0.2%Zr和0.1%Hf(原子分数)微合金化对其持久性能的影响。结果表明:提高温度和增加应力均使铸造TiAl合金定向层片组织的持久寿命降低,其中试验温度对持久寿命的影响幅度相对更大,在相同应力下(300 MPa),当温度由750℃提高到800℃时,持久寿命降低超过100 h。微量Zr,Hf对铸造TiAl合金层片组织的择优取向特征均没有影响,对合金的持久寿命改善作用与温度、应力密切相关,例如800℃/220 MPa较低应力下添加微量Zr使合金的持久寿命由150 h提高到320 h,然而在750℃/350 MPa,800℃/260 MPa,300 MPa等较高应力载荷下,微量Zr,Hf的作用明显减小。由试验应力与Larson-Miller参数的关系可发现,与微量Hf相比,微量Zr在不同应力条件下对合金提高持久强度的作用更大。另外,本实验条件下TiAl合金定向层片组织持久塑性均大于10%,无蠕变脆化倾向;添加微量Zr,Hf可使合金在不同温度和应力条件下的持久塑性保持在20%～40%之间,较基础合金更稳定。The creep rupture properties of cast Ti-47.5Al-2.5V-1.0Cr alloys with preferred orientation lamellar microstructure,were investigated under（220～350） MPa at（750～800） ℃,and the effects of 0.2% zirconium and 0.1% hafnium（atom fraction） on creep rupture properties of cast TiAl alloy were studied respectively.The results showed that the creep rupture life of cast TiAl alloys with this microstructure were reduced with increasing the temperature and stress,of which the temperature relatively had a greater influence,at the same stress（300 MPa）,when the temperature went up from 750 to 800 ℃,the rupture life reduced more than 100 h.Adding minor Zr,Hf did not change the characteristic of preferred orientation lamellar microstructure of cast TiAl alloy,and the effect on the creep rupture life was relative with temperature and the stress intimately.At low stress such as 800 ℃/220 MPa,adding Zr increased the rupture life from 150 to 320 h,while the effect became small obviously at high stress such as 750 ℃/350 MPa,800 ℃/260 MPa,300 MPa.It was found that adding minor Zr was more beneficial to the creep rupture strength of cast TiAl alloy than minor Hf through the relationship between tested stress and Larson-Miller parameters.In addition,rupture ductility of cast TiAl alloys with preferred orientation lamellar microstructure were more than 10%,which indicated that no creep embrittlement tendency existed in this cast TiAl alloy;adding minor Zr,Hf could keep the rupture ductility between 20% ～40% under different temperatures and stress conditions.

关 键 词：铸造TIAL合金 定向层片组织 持久性能 微合金化 

分 类 号：TG146[一般工业技术—材料科学与工程]