DZ125鎳基合金蠕變期間的組織演化與元素擴散遷移率Microstructure evolution and element-diffusion mobility of DZ125 nickel-based superalloy during creep

通過蠕變性能測試及組織形貌觀察，結(jié)合元素擴散遷移率計算，研究DZ125合金在1 040 ℃蠕變期間的組織演化規(guī)律。結(jié)果表明：高溫蠕變期間，合金在枝晶間/干區(qū)域發(fā)生不均勻的組織演化，枝晶間區(qū)域形成的筏狀γ′相尺寸粗大，而枝晶干區(qū)域γ′相沿(001)晶面形成細小的 N-型篩網(wǎng)狀筏形結(jié)構(gòu)，且γ基體相連續(xù)充填在篩網(wǎng)狀γ′相之間，可保證合金的高塑性。在1 040 ℃、137 MPa蠕變期間，合金枝晶干區(qū)域的γ′相經(jīng)3 h轉(zhuǎn)變成筏狀結(jié)構(gòu)，隨施加應力的降低，γ′相發(fā)生筏形化轉(zhuǎn)變的時間延長；其中，Al、Ta具有較高擴散遷移率是促使合金發(fā)生較快筏形化轉(zhuǎn)變的主要原因。

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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