摘要
采用显微硬度计、扫描电子显微镜(SEM)、原子探针层析(APT)技术研究了在标准热处理过程中及720℃时效初期(时效至128 h)718Plus合金的显微组织以及成分的演变规律。结果表明:718Plus合金的硬度在788℃炉冷至704℃后明显上升,在720℃时效至64 h时达到最大值459.3HV±8.5HV,硬度变化与γ′相的析出长大有关。随着热处理的进行,Ti、Al、Nb元素的分配系数逐渐增大,球形γ′相的直径、体积分数逐渐增大。γ′相的析出长大由Ti、Al、Nb元素在基体中的扩散控制,扩散程度采用元素的分配系数进行表示。在整个热处理过程中,Ti、Al、Nb元素在γ′相与基体之间的分配行为造成γ′相的直径、体积分数的变化。此外,在基体中分散着纳米级γ′团簇,其尺寸和数量密度在热处理过程中基本不变。
The evolutions of microstructure and composition in 718Plus alloy during standard heat treatment and aged at 720℃for 1-128 h were investigated by micro-hardness tester,scanning electron microscopy(SEM),atom probe tomography(APT).The results show that the hardness of the alloy increases significantly from 788℃to 704℃with furnace cooling,and reaches the peak value of 459.3HV±8.5HV after being aged at 720℃for 64 h.The change of hardness is related to the precipitation of sphericalγ′phase.With the prolonging of heat treatment,the diameter and volume fraction ofγ′phase gradually enhance,and the partition ratios of Ti,Al and Nb elements gradually increase.The growth ofγ′phase is controlled by the diffusion of Ti,Al and Nb elements,and then the partition ratios of the elements are used to indicate the degree of diffusion of each element.Throughout the heat treatment process,the distribution of Ti,Al and Nb elements between theγ′phase and the matrix brings about the change of the diameter and volume fraction ofγ′phase.High density nano-sizeγ′clusters disperse in theγmatrix,their size and number density remain constant during the heat treatment process.
作者
支雅倩
张孟超
唐榕卿
李慧
ZHI Ya-qian;ZHANG Meng-chao;TANG Rong-qing;LI Hui(Key Laboratory for Microstructures,Shanghai University,Shanghai 200444,China)
出处
《中国有色金属学报》
EI
CAS
CSCD
北大核心
2023年第1期55-67,共13页
The Chinese Journal of Nonferrous Metals
基金
国家重点研发项目(2016YFB0700401)。
