Elaboration of 316L/Cu composite alloy using a hybrid PVD/SPS process.

Powder metallurgy is an ideal field for developing advanced materials with complex geometries and compositions. While, iron-based alloys produced through Spark Plasma Sintering often exhibit residual porosity, adding small amounts of copper provides several benefits: it lowers the sintering temperature, eliminates pores due to its excellent wettability, reduces stress concentrations, and prevents microcracks formation. The localization of copper at the grain boundaries of steel powder particles enables the design of an alloy with a controlled microstructure, thus enhancing its mechanical performance as well as its resistance to corrosion and oxidation. The innovative hybrid approach presented in this work, combines Physical Vapor Deposition (PVD) and Spark Plasma Sintering (SPS) processes. In this study, the development of a 316L alloy with copper-enriched powder particle boundaries is investigated. Surface functionalization of the powders is performed using an inhouse-designed PVD chamber with an original configuration. This synthesis method ensures more precise control over the amount and distribution of copper at the grain boundaries of the powder particles, making it easier to achieve a homogeneous material and enhanced optimization of its mechanical performance. The influence of the copper layer thickness on mechanical performance and on the microstructure after sintering is assessed using several characterization techniques. The bulk composite materials produced exhibit a network-type structure. Increasing the copper content beyond 0.52 wt.% leads to a rise in the elongation at break of the sintered samples. Although hardness tends to decrease slightly with copper addition, copper effectively reduces porosity except at very low concentrations.