In-Situ Preparation and Properties of Ultrafine Cemented Carbide Through Spark Plasma Sintering

Abstract

VC and Cr3C2 grain growth inhibitors (GGIs) and WC ultrafine cemented carbides were synthesized in-situ by spark plasma sintering (SPS) with W, C, Co, V, and Cr as raw materials. The effects of sintering parameters and difference in the particle size (50/500 nm) of raw materials on the microstructure and performance of the alloys were evaluated. The results showed that the specimen has high hardness and toughness (2059.10 kgf/mm2, KIC 14.06 MPa m1/2) prepared at 1400 °C for 8 min under a pressure of 35 MPa with the raw material particles having an equivalent spherical diameter of 50 nm, and an additive content of 0.8 wt.%. Compared to the samples with a raw material particle size of 500 nm, the Vickers hardness and density increased by 8.96% and 4.37%, respectively, and the fracture toughness is significantly improved by 40.88%. Both large and small grains are present in the sample, the small-size grains provide the sample with better hardness and the large-size grains endow the sample with excellent toughness. The SPS and in-situ synthesis methods can optimize the alloy microstructure, uniform distribution of grain inhibitors, and enhance the performance of the alloy.

Keywords: Cemented carbides, Grain growth inhibitors, Spark plasma sintering, mechanical properties