Effect of spark plasma sintering process on the microstructure and properties of NiCoCr multi-principal element alloys

This study investigates the effects of spark plasma sintering (SPS) on the microstructure, mechanical properties, and electrochemical corrosion behavior of NiCoCr multi-principal element alloys (MPEAs), with the aim of providing guidance for the fabrication of high-performance MPEA components using SPS technology. NiCoCr alloy powders were prepared via gas atomization. Preliminary sintering trials were conducted under three conditions: 900 ℃ for 5 minutes at 30 MPa, 1 000 ℃ for 5 minutes at 30 MPa, and 1 000 ℃ for 0 minute at 40 MPa. Based on the microstructural evaluation of these samples, optimal sintering parameters were selected for the main experiments: 900 ℃ for 15 minutes at 30 MPa, 1 000 ℃ for 15 minutes at 30 MPa, and 1 100 ℃ for 15 minutes at 30 MPa. The sintered samples were then subjected to microstructural characterization, uniaxial tensile testing, and electrochemical corrosion testing. As the sintering temperature increased, the alloy's strength decreased significantly, with the yield strength dropping from 835 MPa to 359 MPa, while plasticity improved markedly, with elongation rising from 22.5% to 61.6%. Furthermore, the alloy's work hardening rate was notably enhanced. Meanwhile, this alloy presents enhanced corrosion resistance, the corrosion current density (I_corr) decreased from 644 nA/cm² to 57 nA/cm², corrosion potential (E_corr) increased from -0.369 mV to -0.249 mV, presenting.The NiCoCr MPEAs produced through SPS exhibited excellent mechanical properties. The alloy sintered at 1 100 ℃ for 15 minutes at 30 MPa demonstrated a favorable balance between mechanical strength and corrosion resistance.