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主要研究了喷射成形镍基高温合金的微观组织特征和时效硬化行为。合金经1140℃,8 h固溶处理,然后在780℃,2~12 h时效处理。分别测试了合金显微硬度、析出相大小及形态、电导率和正电子湮没寿命与时效时间的关系。结果表明,在时效8 h时,显微硬度达到最大值,此时γ’长大到临界尺寸56 nm。然而,时效时间超过8 h,合金显微硬度降低,这是由于γ’长大超过了其临界尺寸。随着时效时间延长至6 h,电导率快速增加到其最大值32%IACS,但是正电子湮没寿命则降低到最小值149 ps,在时效时间为10 h时,正电子湮没寿命达到最大值297 ps。这是由在时效过程中γ’尺寸的变化以及缺陷浓度的变化引起的。
The microstructural characteristics and age-hardening behavior of spray-cast nickel-base superalloy were mainly studied. The alloy was solution treated at 1140 ℃ for 8 h and then aged at 780 ℃ for 2 ~ 12 h. The relationship between the microhardness of the alloy, the size and morphology of the precipitated phase, the electrical conductivity, the lifetime of positron annihilation and the aging time were tested respectively. The results showed that the microhardness reached its maximum at 8 h, and γ ’increased to the critical size of 56 nm. However, when the aging time exceeds 8 h, the microhardness of the alloy decreases, because γ ’grows beyond its critical size. As the aging time increased to 6 h, the conductivity rapidly increased to 32% IACS, but the positron annihilation lifetime decreased to a minimum of 149 ps. At the aging time of 10 h, the positron annihilation lifetime reached the maximum value of 297 ps This is caused by the change of γ ’size and the change of the defect concentration during aging.