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赵广迪,臧喜民.W对难变形高温合金U720Li热塑性特征和γ′析出行为的影响[J].稀有金属材料与工程(英文),2021,50(8):2867~2875.[Zhao Guangdi and Zang Ximin.Effect of W on the thermal plasticity and γ′ precipitation behavior of hard-deformed superalloy U720Li[J].Rare Metal Materials and Engineering,2021,50(8):2867~2875.]
Effect of W on the thermal plasticity and γ′ precipitation behavior of hard-deformed superalloy U720Li
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Received:August 28, 2020  
Key words: hard-deformed superalloy  tungsten  thermal plasticity  γ′ precipitation
Foundation item:国家自然科学基金资助(项目号51904146,U1960203)
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Zhao Guangdi and Zang Ximin  
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      In this work, U720Li castings with different W contents (1.02 wt.%, 0.52 wt.% and 0 wt.%) were prepared by vacuum induction melting and subsequently homogenized. The effect of W on hot deformation behavior and fracture characteristics of as-homogenized U720Li alloy was studied emphatically. The 1000 ℃ tensile test results of homogenized and furnace cooled alloys revealed that with the reduction of W content the deformation resistance decreased gradually, and when the W content was reduced to zero the tensile plasticity was greatly improved and the fracture mode was shifted from intergranular fracture to a mixed-mode of intergranular and transgranular fracture. For both furnace-cooled and air-cooled alloys, with the reduction of W addition the grain-interior microhardness decreased gradually, the size of precipitation strengthening phase γ′ increased and the volume fraction of γ′ decreased markedly. The main reason for the influence of W on deformation resistance and thermal plasticity is that the decrease of W not only reduced the solid solution strengthening, but also modified the characteristic of γ′ which promoting the occurrence of dynamic recrystallization. In addition, the distribution of W in U720Li alloy has been revealed in this paper, i.e., W is mainly enriched in the γ matrix, and the mechanism by which W influencing the precipitation of γ′ was discussed accordingly in the text.