Re对一种新型镍基高温合金组织稳定性的影响

为了解Re对一种新型镍基高温合金组织稳定性的影响,采用扫描电镜观察了合金经长期时效后的样品微观组织,并利用透射电镜分析长期时效后析出的新相.实验结果表明,质量分数为1%～4%Re的合金经热处理后,组织由γ相、γ’相和碳化物MC、M23C6组成,当Re含量达到4%时,晶内析出了针状的M23C6.经长期时效后,随Re含量增加,合金中γ'相长大速率下降,合金的组织稳定性恶化,900℃超过1 000 h时效的含4%Re合金中出现针状σ相.因此,所研究合金中Re的含量应低于4%.

Effects of Re on microstructure stability in a new Ni-based superalloy

For finding out the effects of Re on microstructure stability in a new Ni-based superalloy,the microstructure of aging sample was observed by Scanning Electron Microscope(SEM),and the new precipitated phase after long term aging was analyzed by Transmission Electron Microscope(TEM).The experimental results show that the microstructure of the four alloys after heat treatment includes γ,γ′,MC carbides and M23C6 carbides.Needle M23C6 precipitates appear in dendrite core when Re content is 4wt % in the alloy.The stability of microstructure is weakened and the growth rates of γ′ phase slow down with the increasing of Re content.There are σ phase precipitates after aging for 1 000 h at 900 ℃ when Re content is 4wt %,so that the Re content should be lower than 4wt% in the alloy.