喷射成形镍基高温合金时效行为（英文）

Age-Hardening Behavior in the Spray Formed Ni-based Superalloy

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 features and age-hardening behaviors of spray formed Ni-based superalloy have been investigated. The alloy was solutioned at 1140 ℃ for 8 h followed by ageing at 780℃ for various time in the range of 2 h to 12 h. The microhardness, γ precipitates size, morphology, electrical conductivity and positron annihilation lifetime as a function of ageing time were measured. The results show that the microhardness reaches a maximum after ageing for 8 h; at that time, the γ＇ precipitates grow up to a critical size of 56 nm. However, when the size of γ＇ precipitates is beyond the critical size, the microhardness decreases. The electrical conductivity rapidly increases up to its maximum value of 32%IACS with further increase of ageing time of 6 h, but the positron annihilation lifetime drops down to its minimum of 149 ps at this moment, and a maximum of 297 ps is reached after ageing for 10 h. The results are attributed to the changes of defect concentration and γ＇ precipitates size evolution during the ageing process.