Premium
Phase Transformation of Nickel‐Rich Phases in Al–Si Alloy Under Thermal Exposure
Author(s) -
Guo Yongchun,
Gao Xusen,
Xia Feng,
Ma Zhijun,
Yang Wei,
Yang Zhong,
Li Jianping
Publication year - 2021
Publication title -
advanced engineering materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 114
eISSN - 1527-2648
pISSN - 1438-1656
DOI - 10.1002/adem.202000814
Subject(s) - brinell scale , materials science , alloy , microstructure , phase (matter) , nickel , metallurgy , transmission electron microscopy , scanning electron microscope , optical microscope , analytical chemistry (journal) , composite material , nanotechnology , chemistry , organic chemistry , chromatography
Al–11.5Si– x Cu– y Ni–Mg alloys with different Cu and Ni contents are prepared. The microstructure of the alloy and phase transformation of Al 3 CuNi are investigated by X‐ray diffraction (XRD), optical microscope, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy‐dispersive spectrometry (EDS). The nickel‐rich phase in Al–11.5Si–3Cu–2Ni–Mg alloy is only Al 3 CuNi phase. With the increase in Cu and Ni content, the Al 3 Ni phase and the Al 7 Cu 4 Ni phase appear, respectively. The alloys are subjected to thermal exposure treatment at 350 and 425 °C, respectively, and hardness tests are performed on alloys of different exposure times. The Brinell hardness of the alloy decreases with the extension of thermal exposure time. It is found that the microstructure of nickel‐rich phases dissolved and granulated after thermal exposure, and the decrease in the Brinell hardness of the alloy is related to the transformation of nickel‐rich phases. The changes of Al 3 CuNi during thermal exposure are studied by means of in situ follow‐up observation. A large number of serrated new phases are deposited on the smooth Al 3 CuNi phase interface during thermal exposure. In addition, the Al 3 CuNi phase break and granulates with time. TEM analysis shows that the new jagged phase formed at the interface of Al 3 CuNi phase is Al 7 Cu 4 Ni phase.