摘要
针对高压涡轮导向叶片服役性能需求特点研发了一种低密度、低成本、高强度Ni3Al基单晶合金IC21.该合金的Re含量不大于1.5%,密度小于8.0 g/cm3.金相法测得合金的初熔温度约为1345℃.经过标准热处理后,IC21合金中γ'相分布均匀,体积分数为80%左右,尺寸约为420 nm,具有较高的γ'相立方化程度和排列有序度.IC21单晶合金在1100℃下抗拉强度为490 MPa,屈服强度为470 MPa,在1100℃,140 MPa条件下的持久寿命可达170.5 h,1150℃,100 MPa条件下的持久寿命可达110.0 h.IC21单晶合金具有良好的高温组织稳定性和较好的抗高温氧化性,1080℃长期热暴露后,没有拓扑密堆相析出,在1100和1150℃大气中100 h的氧化动力学曲线遵循抛物线规律,氧化增重速率分别为0.015和0.045 mg/(cm2·h).组织结构分析表明,该单晶合金的高温强度主要来源于高的γ'相含量、高的合金错配度和致密的界面位错网结构.γ'
According to the requirement of high-pressure turbine guide vane during service, the aim of this work is to design a single crystal Ni3Al-based alloy named IC21 with low density, low cost, and high strength which can be used as high-pressure turbine guide vane material. The mass fraction of the Re has been limited less than 1.5% on purpose. The single crystal bars of IC21 were prepared by high rate solidification method.The density of IC21 is 8.0 g/cm3 and the incipient melting temperature was identified by metallography. After standard heat treatment, the distribution of the γ＇ precipitates is uniform with the average size of about 420 nm,and volume fraction of 80%. The tensile and yield strengths at 1100 ℃ are 490 and 470 MPa, respectively. Moreover, IC21 shows superior creep properties, the stress-rupture life at 1100 ℃,140 MPa is 170.5 h and at 1150 ℃,100 MPa still remains 110.0 h. The microstructure stability of IC21 alloy at 1080 ℃ for as long as 1000 h were evaluated. The results show that no precipitated phase exists during thermal exposure at 1080 ℃, which exhibits good stability. The oxidation kinetic curves of IC21 alloy follows a parabolic rate law in different oxidation stage during cycle oxidation for 100 h in air. IC21 alloy has a good high temperature oxidation resistance, the strengthening mechanism are attributed to high volume fraction of γ＇ phase, large negative misfit and well-established interface networks.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2015年第10期1279-1287,共9页
Acta Metallurgica Sinica
基金
国家自然科学基金项目51371014
国家自然科学基金联合基金项目U1435207资助~~
关键词
NI3AL
IC21单晶合金
低成本
低密度
高温力学性能
抗氧化性能
Ni3Al
IC21 single crystal alloy
low cost
low density
high temperature strength
high temperature oxidation resistance
