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研究GH720Li合金经标准热处理(1105℃,4 h→油冷+650℃,24 h→空冷+760℃,16 h→空冷)后分别在720℃时效0~5000 h和800℃时效0~1000 h后γ!强化相的演变规律.合金在720℃,5000 h时效后一次γ'相的尺寸、形态以及数量基本不发生变化;在720℃,200 h时效后,二次γ'相发生明显粗化;500 h后出现不均匀长大.相应地,500 h前硬度下降速率大,500 h后趋于平稳.在800℃,500 h时效后,一次γ'相发生粗化;800℃,100 h时效后,二次γ'相发生明显粗化且不均匀长大.500 h前硬度下降斜率很大,500 h后硬度仍有明显下降趋势.720℃及800℃时二次γ'相粗化行为是以扩散控制的粗化机制为主导.γ'相平均半径与时效时间满足立方根关系,符合L-S-W(Lifshiz-Slyozov-Wanger)理论.
The effects of heat treatment at 110 ℃, 4h → oil cooling + 650 ℃, 24 h → air cooling + 760 ℃, 16 h → air cooling were studied respectively. The effects of aging treatment at 720 ℃ for 0-5000 h and 800 ℃ for 0-1000 h After γ-phase was annealed at 720 ℃ for 5000 h, the size, shape and amount of primary γ 'phase did not change basically. After 200 h aging at 720 ℃, the secondary γ' phase was obviously thick After 500 h, the rate of hardness decline was large and stabilized after 500 h. At 800 ℃ for 500 h, a γ 'phase coarsened at 800 ℃ and 100 h after aging, the secondary γ 'phase obviously coarsens and grows inhomogeneously, and the slope of hardness decline is large before 500 h, and the hardness still shows a significant decrease after 500 h. The chemical behavior is dominated by the roughening mechanism of diffusion control.The average radius of γ 'phase and the aging time satisfy the cubic root, which is in accordance with the theory of LSW (Lifshiz-Slyozov-Wanger).