# Heat Treatment Effects on Laser Powder Bed Fused CuNi2.5SiCr Alloy: Microstructure, Hardness, Electrical, and Thermal Conductivity

## TL;DR

This paper studies how heat treatment affects the properties of a copper alloy made using laser powder bed fusion, showing optimal hardness and conductivity at specific temperatures.

## Contribution

The study demonstrates successful laser powder bed fusion of a CuNi2.5SiCr alloy at low laser powers and evaluates the effects of heat treatment on its properties.

## Key findings

- Samples fabricated at 67.2 W achieved a relative density of 96.8%.
- Heat treatment at 850 °C improved hardness and thermal conductivity to 20 W/mK.
- As-fabricated samples showed the highest electrical conductivity of 1.07 × 10⁶ S/m.

## Abstract

Additive manufacturing of copper alloys remains challenging due to their high reflectivity and thermal conductivity, which limit laser energy absorption and increase energy consumption. In this study, the laser powder bed fusion of a copper-based CuNi2.5SiCr alloy is demonstrated using low laser powers (67.2–100.8 W). Samples fabricated at 67.2 W achieved a relative density of 96.8%, with no significant improvement observed at higher laser powers. The post-process heat treatments were conducted at 750 °C, 850 °C, and 950 °C to investigate their influence on microstructure, hardness, electrical and thermal conductivity. Heat treatment at 850 °C resulted in the highest hardness, improved microstructural uniformity and 20 W/mK thermal conductivity, while the as-fabricated samples exhibited the highest electrical conductivity (1.07 × 106 S/m).