研究了一种抗热腐蚀高温合金K44在800，850 和900℃经10000小时长期时效后的 γ’组织变化和拉伸性能.结果表明，γ’ 沉淀相的长大动力学符合Lifshitz-Slyozof-Wagner 熟化规律，长大激活能为 255 kJ/mol.相对较小的γ’相出现了和弹性应变能相关的形态不稳定现象.合金屈服强度随时效温度升高和时效时间的延长而降低，可以由Labusch-Schwarz 强化理论来解释，但塑性却出现了波动. 合金的强化机制为强相互作用位错对切割机制.
The effect of long-term aging on the γ’ characteristics and the mechanical properties have been investigated in a corrosion resistant nickel-base superalloy K44 aged isothermally in the temperature range of 800-900℃ up to 10000 h. SEM observation reveals that the coarsening kinetics of γ’ follows Lifshitz-Slyozof-Wagner (LSW) theory at different temperatures, with the activation energy of 255 kJ/mol for growth. Morphological instability occurs in relatively small γ’ precipitates during aging process. At room temperature (RT) and 900℃, yield strength decreases with aging temperature and aging time increasing, while fluctuation of elongation is observed. The dependence of the yield stress on particle size is explained by Labusch-Schwarz hardening theory rather than classical strengthening theory on coherency and mismatch strengthening. Shearing of strong-coupled dislocations is dominant strengthening mechanism.
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