Diffusional behaviors and mechanical properties of Cu-Zn system

The growth behaviors, diffusion kinetics and mechanical properties of Cu-Zn intermetallic compounds (IMCs) have been studied. The formation of three IMCs beta'(CuZn), gamma(Cu5Zn8) and epsilon(CuZn5) has been verified in Cu-Zn diffusion zone between 563 and 653 K. The thickening of all three IMCs followed a parabolic growth law, indicating a diffusion-control mechanism. The growth constants and growth activation energy of IMCs were estimated. With the EPMA, the composition profiles along the diffusion direction were detected, then the diffusion coefficients and activation energy of diffusion were extracted for individual phases. The hardness, Young's modulus and creep stress index of the IMCs were obtained from the load-displacement curve in nanoindentation. Cu5Zn8 has the highest hardness of 6.81 GPa and highest Young's modulus of 186.76 GPa, respectively, while CuZn5 has the smallest creep stress index of 13.77. (C) 2019 Elsevier B.V. All rights reserved.