Study of ordered phase precipitation behaviour and hardening mechanism of Au-20Ag-10Cu alloy during deformation-aging treatment.

With the rapid development of aerospace technology, the demand for a longer service life of Au-Ag-Cu alloy as conductive slip rings is increasing. Therefore, it is important to improve the hardness of the alloys in order to prolong their service life. Deformation-aging can improve the hardness of many alloys. The effect of the deformation-aging process of Au-20Ag-10Cu (wt%) alloy was investigated on the microstructure and properties, which characterized by DSC(Differential Scanning Calorimeter), XRD(X-ray Diffraction), EBSD(Electron Backscatter Diffraction), TEM(Transmission Electron Microscope) characterization techniques, microhardness and electrical conductivity testing methods. The results indicated that the microhardness increases and the conductivity decreases gradually with the increase of deformation rate. As the aging time increasing, the content of face-centered tetragonal AuCu I ordered phase increases, and thus the hardness increases gradually. The maximum hardness value of 307.44 HV was obtained after undergoing 70 % deformation and then aged at 300 ℃ for 16 h with the electrical conductivity values of 8.40 MS·m−1. This result indicated that both higher hardness and higher electrical conductivity of Au-20Ag-10Cu (wt%) alloy could be obtained, which ensures the requirements in the field of electrical contact materials. • The alloy with 70 % deformation rate and aged at 300 ℃ for 16 h had the maximized hardness value. • The transformation process of the matrix phase into the ordered phase can be significantly facilitated by increasing the aging time. • After aging at 300 ℃, the coherent boundary of {100} α 0 //{100}AuCu Ⅰ occurred because of the small lattice mismatch. [ABSTRACT FROM AUTHOR]