Effect of Ni Content on Microstructure and Characterization of Cu-Ni-Sn Alloys.

Sanming Du,Xiaochao Wang,Jingbo Wang,Zhen Li,Zhenghai Yang

doi:10.3390/ma11071108

Abstract

Cu-xNi-5Sn (wt %) alloys with a different Ni content were prepared by a powder metallurgy method. The effect of Ni content on the hardness and yield strength of Cu-xNi-5Sn (wt %) alloys was investigated. The microstructure, composition, and morphology of Cu-xNi-5Sn (wt %) alloys were observed by X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), and cold field emission scanning electron microscope (FESEM), respectively. Results indicate that the hardness and yield strength firstly increase and then decrease with the increase of Ni content and reach up to a maximum when Ni content is 12.5 wt %. Furthermore, the formation of the sandwich structure and needle-like phase is found in the grain, the grain boundary and intragranular precipitates are rich in both the Ni and Sn phase. The formation of the inerratic and suitable lamellar precipitates of sandwich structure and needle-like phase can be responsible for the good mechanical properties of the Cu-12.5Ni-5Sn alloy after aging treatment. The sandwich structure and need-like phase that were observed by FESEM can contribute to clarify the morphology of Cu-Ni-Sn alloys.

Highlights

The Cu-Ni-Sn alloys attracted wide interest in electronic and mechanical industries because of high strength, excellent stress relaxation, corrosion resistance, good thermal and electrical conductivity, and so on [1,2,3]
The sandwich structure and need-like phase that were observed by field emission scanning electron microscope (FESEM) can contribute to clarify the morphology of Cu-Ni-Sn alloys
Zhao and Notis [2,11] investigated the microstructures and the transformation kinetics of Cu-15Ni-8Sn alloy and Cu-7.5Ni-5Sn alloy under different aging conditions, and established a time-temperature-transformation diagram, respectively, which laid the foundation for the selection of heat treatment schedule in the future

Summary

Introduction

The Cu-Ni-Sn alloys attracted wide interest in electronic and mechanical industries because of high strength, excellent stress relaxation, corrosion resistance, good thermal and electrical conductivity, and so on [1,2,3]. The Cu-Ni-Sn alloys are expected as candidates for the nocuous Cu-Be alloys with the high strength in the application of electrical springs, connectors, bearings, [3,4,5], etc. It is known that the Cu-Ni-Sn alloys are strengthened by age-hardening. Zhao and Notis [2,11] investigated the microstructures and the transformation kinetics of Cu-15Ni-8Sn alloy and Cu-7.5Ni-5Sn alloy under different aging conditions, and established a time-temperature-transformation diagram, respectively, which laid the foundation for the selection of heat treatment schedule in the future. Peng et al [12] reported that the stress-strain curve of

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Conclusion