Microstructure and properties of Cu–2.8Ni–0.6Si alloy

The phase transformation behavior and heat treatment response of Cu–2.8Ni–0.6Si (wt%) alloy subjected to different heat treatments were studied by X-ray diffraction, transmission electron microscopy observation, and measurement of hardness and electrical conductivity. The variation of hardness and electrical conductivity of the alloy was measured as a function of aging time. On aging at the temperature below T _R (500–550 °C) in Cu–2.8Ni–0.6Si alloy, the transformation undergoes spinodal decomposition, DO₂₂ ordering, and δ-Ni₂Si phase. On aging at the temperature above T _R (500–550 °C), the transformation products were precipitations of δ-Ni₂Si. The free energy versus composition curves were employed to explain the microstructure observations.