Microstructural Characterization and Wear Resistance of 60 wt.%, 70 wt.%, and 80 wt.% WC-NiCrBSi Thin Walls Deposited Using Plasma Transferred Arc Additive Manufacturing

Plasma transferred arc additive manufacturing (PTA-AM) was used to deposit 60 wt.%, 70 wt.%, and 80 wt.% WC-NiCrBSi metal matrix composites. The 60 wt.% samples had a homogeneous distribution of WC particles. At 70 wt.% and 80 wt.%, two defects were found in the microstructure: areas completely void of WC, termed denuded regions, and large pores. The microstructure of the 60 wt.% sample consisted of blocky complex carbides [(Ni4W2Cr2Si)C-3], gamma-Ni cellular dendrites, a halo around the primary dendrites, and a lamellar eutectic of Ni3Si/Ni3B. There is increased thermal degradation of WC at 70 wt.% WC, causing a wider array of complex carbides and higher W contents in the gamma-Ni dendrites and the halo. Thermo-calc software was used to model the solidification of NiCrBSi with 10 wt.% W to determine the effect that W addition has on the solidification of the Ni alloy, and the results were compared to the 60 wt.% and 70 wt.% WC-NiCrBSi PTA-AM deposits. The abrasive wear resistance and the impact resistance of 60 wt.%, 70 wt.%, and 80 wt.% WC deposited with PTA-AM were comparable to a 60 wt.% W-CNiCrBSi PTA overlay.