DZ125镍基合金蠕变期间的组织演化与元素扩散迁移率Microstructure evolution and element-diffusion mobility of DZ125 nickel-based superalloy during creep

通过蠕变性能测试及组织形貌观察，结合元素扩散迁移率计算，研究DZ125合金在1 040 ℃蠕变期间的组织演化规律。结果表明：高温蠕变期间，合金在枝晶间/干区域发生不均匀的组织演化，枝晶间区域形成的筏状γ′相尺寸粗大，而枝晶干区域γ′相沿(001)晶面形成细小的 N-型筛网状筏形结构，且γ基体相连续充填在筛网状γ′相之间，可保证合金的高塑性。在1 040 ℃、137 MPa蠕变期间，合金枝晶干区域的γ′相经3 h转变成筏状结构，随施加应力的降低，γ′相发生筏形化转变的时间延长；其中，Al、Ta具有较高扩散迁移率是促使合金发生较快筏形化转变的主要原因。

By means of creep-curve measurements and microstructure observations, combined with the calculation of element-diffusion mobility, the microstructure-evolution regularity of DZ125 nickel-based superalloy during creep at 1 040 ℃ was investigated. The results show that, during high-temperature creep, inhomogeneous microstructure evolution occurs in the interdendrite and dendrite arm regions. The coarser rafted γ′ phase appears in the interdendrite regions, the fine rafted γ′ phase with the mesh-like N-type structure on (001) plane forms in the dendrite arm regions, and the γ matrix phase fills continuously between the mesh-like rafted γ′ phase to ensure the better plasticity of the alloy. During creep at (1 040 ℃, 137 MPa), the cuboidal γ′ phase in the dendrite arm region transforms into the rafted structure after being crept for 3 h. As the applied stress decreases, the rafted time of γ′ phase prolongs. Thereinto, the bigger diffusion mobilities of elements Al and Ta are the main reason for the alloy occurring rapidly microstructure evolution.

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