Microscopic phase-field simulation for precipitation behavior of Ni-Al-Cr alloy during two-step aging

• Published in: Transactions of Nonferrous Metals Society of China Vol. 18; no. 4; pp. 930 - 937
• Main Author: 张济祥 陈铮 梁敏洁 王永欣 来庆波
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.08.2008; School of Materials Science and Engineering, State Key Laboratory of Solidification Processing,Northwestern Polytechnical University, Xi'an 710072, China
• Subjects: microscopic phase-field; Ni-Al-Cr alloy; order parameter; precipitation mechanism; two-step aging; 两步老化; 显微相场模拟; 沉淀机制; 镍铝铬合金; microscopic phase-field; Ni-Al-Cr alloy; precipitation mechanism; two-step aging; order parameter
• ISSN: 1003-6326
• DOI: 10.1016/S1003-6326(08)60161-2

Based on the microscopic phase-field model, the pre-aging temperature effects on the precipitation mechanism and microstructure evolution during two-step aging for Ni75A19Cr16 alloy were simulated. The results show that the early precipitation mechanism of Ll2 phase is the mixed mechanism of spinodal decomposition and non-classical nucleation growth, whereas the early precipitation mechanism of DOzz phase is spinodal decomposition when the pre-aging temperature is 873 K. The early precipitation mechanism of LIz phase is non-classical nucleation growth, whereas the early precipitation mechanism of DOzz phase is spinodal decomposition when the pre-aging temperature is 973 K. Under the effects of elastic strain energy, the cubic particles exhibit directional alignment along [ 100] and [010] directions during the late precipitation, which is more obvious at lower pre-temperature. DOzz phases appear earlier than Llz phases under these two kinds of precipitation processes; and the nucleation incubation time becomes long with the increase of pre-temperature.