Upcycling copper chips into Cu–Fe alloys via coating-assisted plasma sintering

Abstract

Upcycling metal machining waste into functional engineering materials offers a sustainable pathway for value-added manufacturing. In this work, a new coated chip plasma sintering (CCPS) strategy was introduced to produce Cu–Fe alloys from discarded copper chips. Copper chips generated by machining were first coated with Fe by arc physical vapor deposition and then consolidated through cold compaction followed by spark plasma sintering. The machining process imposed severe plastic deformation on the Cu chips, producing an ultrafine microstructure prior to consolidation. During sintering, disruption of the Fe coating and surface oxides facilitated direct metallic contact and accelerated interfacial diffusion, enabling effective densification and bonding. The consolidated alloy contained a Cu-rich matrix with a small Fe addition (~ 0.25 wt%) and exhibited twins, refined grains, and dispersed Fe/oxide phases. These features resulted in marked strengthening, with the alloy reaching a yield strength of ~ 280 MPa, ultimate tensile strength of ~ 307.9 MPa, and hardness of ~ 116.5 HV. Although elongation decreased to ~ 11.6%, the alloy retained relatively high electrical conductivity with only a slight increase in resistivity. The proposed CCPS route demonstrates an efficient and sustainable method for converting copper waste into Cu-based alloys with an attractive combination of structural and electrical properties.