Microstructure evolution and precipitation behaviour of the Cu-Ni-Si-Cr alloy based on twin-roll strip casting

ABSTRACT

The twin-roll strip casting (TRSC) process was introduced because of its sub-rapid solidification characteristics, and the element segregation and ageing precipitation of the Cu-6Ni-1.4Si-0.1Cr alloy were studied. The results are as follows: TRSC can effectively refine grain size and inhibit the segregation of the Cu-6Ni-1.4Si-0.1Cr alloy. Two types of precipitates are formed mainly during the ageing process: disk-shaped δ-Ni₂Si and rod-shaped β-Ni₃Si. The comprehensive properties of the alloy are improved, and the precipitation strengthening mechanism is either from the dislocation shearing mechanism or the Orowan mechanism in different stages of ageing. The Cu-6Ni-1.4Si-0.1Cr alloy achieves optimum performance after ageing at 350°C for 4 h, where the tensile strength and conductivity are 1112 MPa and 27.35% IACS, respectively. The Avrami equations were established for the alloy to describe the kinetics of phase transformation and electrical conductivity during ageing, and the calculated results are consistent with the experimental data.

KEYWORDS:

• TRSC
• micro-segregation
• Cu-6Ni-1.4Si-0.1Cr alloy
• precipitation strengthening

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National MCF (Magnetic Confinement Fusion) Energy R&D Program of China [grant number 2018YFE0306102]; Postdoctoral Science Foundation of China [grant number 2021M701167].