钽元素对Co-8.8Al-9.8W合金微观组织和力学性能的影响规律

Effect of Tantalum on Microstructure and Mechanical Properties of Co-8.8Al-9.8W Alloy

为了研究合金化Ta(钽)元素对Co-8.8Al-9.8W高温合金微观组织和力学性能的影响,通过对Co-8.8Al-9.8W-x Ta(x=0,1,2,4,6,原子分数,%,下同)合金微观组织和室温压缩性能的研究发现:铸态合金组织由γ基体相和衬度较亮的晶间相组成,枝晶间析出的白色衬度晶间相随着Ta含量的增加逐渐增多,并与γ基体相呈现出典型的共晶组织。经过1300℃/4 h的固溶处理和900℃/50 h的时效热处理,γ基体上析出均匀细小的γ′强化相,并且随Ta元素含量的增加,团簇状二次相(μ相、χ相和β相)逐渐增多。Co-8.8Al-9.8W-x Ta(x=0,1,2,4,6)合金在铸态和热处理状态下的显微硬度均随着Ta含量的增加而增加,其中,6Ta合金在铸态和热处理状态下均表现出最大的显微硬度,分别为567 HV和625 HV。室温压缩下,除1Ta合金外,其他合金的屈服强度σ_(0.2)随着Ta元素含量的增加而逐渐增大,6Ta合金表现出1259 MPa的最大屈服强度;合金的极限抗压强度随着Ta元素含量的增加而先增大后减小,且在4Ta合金中表现出2522 MPa的最大抗压强度;所有合金中2Ta合金表现出22.95%的最大塑性变形能力。

In order to study the effect of Ta(tantalum)element on the microstructure and mechanical properties of Co-8.8Al-9.8W superalloys at room temperature,the study on the microstructure and compressive properties of Co-8.8Al-9.8W-x Ta(x=0,1,2,4,6,atomic fraction,%)superalloy at room temperature show that the as-cast superalloy microstructure is composed ofγmatrix phase and white intergranular phase,and the white inter-granular phase precipitated between dendrites gradually increased with the increase of Ta content,and showed a typical eutectic microstructure with theγmatrix phase.After 1300℃/4 h solution treatment and 900℃/50 h aging heat treatment,a uniform and fineγ′strengthe-ned phase was precipitated on theγmatrix,and with the increase of Ta element content,the cluster-like secondary phase(μphase,χphase andβphase)gradually increased.The microhardness of Co-8.8Al-9.8W-x Ta(x=0,1,2,4,6)alloy in as-cast and heat-treated state increased with the increase of Ta content,among which the 6Ta alloy had the maximum microhardness in both as-cast and heat-treated conditions,respectively 567HV and 625HV.Under room temperature compression,the yield strength σ_(0.2) of the alloy gradually increased with the increase of Ta element content except for 1Ta alloy,and the 6Ta alloy had a maximum yield strength of 1259 MPa;the maximum compressive strength of the alloy showed to increase first and then decrease with Ta content increases and the 4Ta alloy had a maximum compressive strength of 2522 MPa;2Ta alloy of all alloys exhibited a maximum plastic deformation capacity of 22.95%.