复合添加Ni和Hf元素对沉淀强化Co-Al-W高温合金组织和力学性能的影响

Effect of Composite Addition of Ni and Hf Elements on the Microstructure and Mechanical Properties of Precipitation Strengthened Co-Al-W Superalloy

研究了Ni和Hf元素对Co-Al-W合金的组织结构的影响,并进行900℃高温压缩试验,测量屈服强度和极限强度。试验结果证明:Hf元素含量为0.5%时,合金主要为γ相和γ′相的两相结构;当Hf元素为1%时,10Ni1Hf合金中出现了Co_(23)Hf_(6)相、20Ni1Hf和30Ni1Hf,40Ni1Hf合金中出现了Co_(23)Hf_(6)相和Co_(2)Hf相。900℃的压缩试验表明,随着Ni元素的增加,合金的屈服强度和极限强度都呈现为先增大后减小的趋势。随着Hf元素增加到1%,10Ni、20Ni合金极限强度和屈服强度均增大,40Ni合金的极限强度和屈服强度均最小,20Ni1Hf合金的屈服强度和抗拉强度均为最大值。因此合金中添加少量的Hf对力学性能是有利的,当Hf含量为1%时导致富Hf有害相的产生。添加一定量的Ni可以提高合金的力学性能,但不能超过20%,过多反而降低其高温强度。

In this paper,the effects of Ni and Hf on the microstructures of a Co-Al-W alloy were investigated,and the yield strength and ultimate strength of the alloys were measured by compression test at 900℃.The experimental results proved thatwhen the content of Hf was 0.5%,the alloy exhibited a dual-γandγ'phases structure.When the Hf element was 1%,Co_(23)Hf_(6) phase presented in 10Ni1Hf alloy,Co_(23)Hf_(6) phase and Co_(2Hf) phase phases formed in 20Ni1Hf,30Ni1Hf and 40Ni1Hf alloys.The yield strength and ultimate strength increased with the incrementof Ni firstly,then decreased,which peaked at 20Ni.As the Hf content increased to 1%,the ultimate and yield strengths of the 10Ni and 20Ni alloys raised,the ultimate and yield strengths of the 40Ni alloy were the smallest,while the yield and ultimate strengths of the 20Ni1Hf alloy were the maximum.The alloying with minor Hf was preferable.It lead to the formation of deleterious Hf-rich phases in the alloys,when the Hf contents was 1%.The addition of Ni within 20%was beneficial to the alloys and the over addition of Ni degrade the strength of the alloys at elevated temperature.