Microstructure and properties of Cu-Cr-Nb alloy powder prepared by argon gas atomization

The Cu-2Cr-1Nb (at%) alloy powder was prepared by close-coupled argon gas atomization. The morphology, microstructure and phase were characterized by SEM, TEM, HRTEM, SAED and XRD. The effects of heat treatment on the microstructure and microhardness of the powder were investigated. The alloy matrix had equiaxed crystal structure, and the second phase was Cr2Nb intermetallic compound in sub-micron and nano-scale. Compared with large powder, the second phase of small powder is finer, and its distribution in the matrix is more uniform, the microhardness of the small powder is higher. After heat treatment at 773 K for 1 h, Cr and Nb precipitated and formed a large number of small precipitates, age hardening and peak aging phenomena occurred, and the peak hardness of the powder reached 130 HV. With the increase of heat treatment temperature, the second phase was coarsened. When the heat treatment temperature was 973 K, the short-time heat treatment hardening and long-time heat treatment softening were shown. However, after the heat treatment at 1223 K, only softening phenomenon was observed. This method can be used to prepare the excellent powder for Cu-Cr-Nb alloy, which can be used as a potential structural material for aerospace. (C) 2019 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.