On the microstructure and dynamic mechanical behavior of Cu–Cr–Zr alloy manufactured by high-power laser powder bed fusion

Abstract

This study explores high-power laser powder bed fusion (LPBF) processing of Cu–Cr–Zr alloy, focusing on its high strain rate dynamic mechanical response and microstructural evolution. The alloy undergoes significant strain hardening during dynamic impact loading, primarily attributed to intensified dislocation interactions and multiplication. This is accompanied by thermal softening induced by adiabatic heating, therefore improving strain accommodation. As the strain rate increases from 4400 s⁻¹ to 11300 s⁻¹, the ultimate compressive strength (UCS) enhances from 173 ± 8 MPa to 489 ± 14 MPa, demonstrating a high strain rate sensitivity (SRS) of ∼ 1. Microstructural examinations reveal that higher strain rates intensify the occurrence of adiabatic shear bands (ASBs), leading to severe localized plastic deformation. These ASBs generate localized stress concentrations, which in turn accelerate crack initiation and propagation through pore formation and coalescence within the ASBs. Despite this severe plastic deformation, texture analysis indicates that the crystallographic texture remains largely stable which suggests that the deformation mechanism is primarily governed by dislocation motion and interaction, rather than by crystal structure reorientation. Overall, the alloy balances strain hardening and strain accommodation at high strain rates, making it well-suited for applications requiring strength and resilience under dynamic impacts.