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采用显微组织观察和JMat Pro相平衡计算和热力学模拟软件等手段研究了一种实验Ni_3Al基单晶高温合金的显微组织和1100℃/90 MPa条件下的持久高塑性变形行为,并分析了持久高塑性变形机制。实验Ni_3Al基单晶合金为γ/γ’两相组织,热处理后合金枝晶干部位γ’相的体积分数为86.0%,其形貌呈接近立方体形。JMat Pro软件在平衡相析出、γ/γ’相点阵常数和γ/γ’点阵错配度方面的计算结果与实验结果吻合的较好。合金1100℃/90 MPa的平均伸长率为148.5%,平均断面收缩率为72.3%。合金在持久变形过程中形成平行于应力轴方向的P型近似筏排组织使位错易于滑移传递从而在高温持久条件下表现出高塑性变形行为。
The microstructure of Ni_3Al-based single crystal superalloy and the long-time high plastic deformation behavior under 1100 ℃ / 90 MPa were studied by means of microstructure observation, phase equilibrium calculation and thermodynamic simulation software of JMat Pro. Long lasting plastic deformation mechanism. The Ni_3Al-based single crystal alloy is γ / γ ’two-phase microstructure. The volume fraction of the γ’ phase in the dendritic dry part of the alloy after heat treatment is 86.0%, and its morphology is nearly cubic. The calculated results of JMat Pro software in equilibrium phase, the lattice constants of γ / γ ’phase and γ / γ’ lattice mismatch are in good agreement with the experimental results. The average elongation of the alloy at 1100 ℃ / 90 MPa was 148.5% and the average reduction of area was 72.3%. The formation of P-type raft tissue parallel to the stress axis during the permanent deformation of the alloy makes the dislocation easy to slip transfer and thus exhibits high plastic deformation behavior under long-term high temperature.