Microstructure and Mechanical Properties of MoNbTaW RHEA Fabricated by Laser Metal Deposition

Refractory high-entropy alloys have great application potential in aerospace and shipbuilding due to their excellent properties, such as high-temperature strength and corrosion resistance. However, due to the vast difference in the melting point of the constituent elements, the formability of the traditional sintered and cast refractory high-entropy alloy parts still has defects. Previous studies added the remelting step under low energy density to obtain a more uniform element distribution, but this inevitably brought challenges to the molding efficiency of the parts and the molding design of complex shapes. In this study, macro-defect-free MoNbTaW RHEA bulks were fabricated on pure titanium substrates by the laser metal deposition technique. The mechanical properties and microstructure morphology of the samples were examined. The powders and various parts of the samples were characterized and analyzed by scanning electron microscopy, energy dispersive spectrometer, and X-ray diffraction. The average yield strength of the alloy was 1320.16 MPa, the average compressive strength was 1855.11 MPa, and the average fracture strain was 15.92%. The average hardness of the top layer was 846.4 HV. The average coefficient of friction for the top layer region of the sample was 0.164219. The wear form was mainly abrasive wear.