摘要
利用喷射成形工艺制备了GH742y高温合金沉积坯锭,对其在780～850℃温度区间进行2～12h短期时效处理;测量了780℃不同时效时间条件下的喷射成形合金和铸造合金的电阻率,从而计算了相应的空位迁移能。采用光学显微镜、扫描电镜和图像分析软件对喷射成形GH742y合金的γ′相形态、尺寸变化及长大动力学进行了研究。结果表明,在时效过程中γ′相逐渐转变为球形,随时效温度的升高和时间的延长γ′相尺寸增加,但温度对其影响比时间更为显著;计算得到合金的扩散激活能为130.9kJ/mol,从而确定其长大动力学方程为■t3-■03=9.4×1013·(tT)·exp(-130.9RT);测得780℃下喷射成形合金的空位迁移能为0.21eV,铸造合金的为1.16eV,因此喷射成形高温合金更容易形成大量的空位,导致其电阻率比铸造合金的高,而激活能值则较小,从而促进了元素扩散速度,缩短了峰时效硬化时间。
A GH742y superalloy billet was prepared by spray forming process, and the morphology, size and growth kinetics of γ＇ precipitate during ageing treatment at 780-850 ℃ for 2-12 h were studied using optical microscope, scanning electron microscope and image analysis. The results showed that the γ＇ precipitate was evolved gradually to be spherical in shape during ageing treatment. The γ＇ particles size increased with the increase of ageing time or temperature. According to the measured diffusion activity energy of 130.9 kJ/mol, the growth kinetics equation of γ＇ precipitate was obtained to be. rt^3 -r0^3 = 9.4 × 10^13 · （t/T）. exp（-130.9/RT）. The low activity energy was attributed to a great deal vacancies in spray formed superalloy. The migration energy of vacancy were obtained to be 0.21 eV and 1.16 eV, respectively, by electrical resistivity measurements for the spray formed superalloy and casted superalloy after ageing treatments. As a result, more vacancies were easily formed in spray formed superalloy than those in the casted alloy. The peak ageing time of the spray formed superalloy is remarkably shortened due to the diffusion acceleration of solute atoms.
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2007年第7期1205-1209,共5页
Rare Metal Materials and Engineering
基金
国防基础科研计划项目资助(K1400061101)
