Aging Behavior and Precipitation Analysis of Cu-Ni-Co-Si Alloy

Abstract

Cu-Ni-Si alloy with a different Co content was prepared by inductive melting and hot rolling. The alloy was solution treated at 950 °C for 1.5 h and aged at 450 °C, 500 °C, and 550 °C for different times. The phase diagram calculation and transmission electron microscopy was used to investigate the effect of Co addition on the aging precipitation behavior of the Cu-Ni-Si alloy. The phase transformation kinetics equation was calculated as well. The results show that, with the increase of aging temperature, the two-phase region of Fcc + Ni2Si in the Cu-Ni-Si ternary diagram would get wider. Some NixSiy phases would also form in the Cu-rich isothermal section. The addition of Co would replace part of Ni to form the (Ni, Co)2Si phase, which inhibits the spinodal decomposition process of the Cu-Ni-Si alloy during the aging process. The precipitated phase of the Cu-Ni-Si alloy with a high content of the Co element is more likely to grow with the extension of aging time. The phase transformation kinetic equations of the Cu-Ni-Si alloy at 450 °C and 500 °C showed good agreement with the experimental results. Furthermore, it can be seen from the precipitation kinetic curve the addition of the Co element accelerates precipitation in the aging process.

Characterizations on Precipitations in the Cu-Rich Corner of Cu-Ni-Al Ternary Phase Diagram

“…A lead frame is of great importance in the integrated circuit, as it supports the bridge between the chip and the external conductor, as shown in Figure 1. Under normal conditions, copper alloys are used for lead frameworks because of their high ductility, thermal conductivity and electrical conductivity [1][2][3]. However, with the development of IC toward high integration and miniaturization, the number of components is increasing, while the distance between components is decreasing.…”