Microstructure and Wear Property of ZrO₂-Added NiCrAlY Prepared by Ultrasonic-Assisted Direct Laser Deposition

For improving the wear properties of NiCrAlY, the 10 wt %, 20 wt % and 30 wt % ZrO₂-added NiCrAlY samples were prepared by ultrasonic-assisted direct laser deposition, respectively. The results showed that the ultrasonic-assisted direct laser deposition can realize the ZrO₂-added NiCrAlY preparation. Furthermore, due to the cavitation effect and agitation of the ultrasound in the molten pool, ultrasonic-assisted could make the upper surface of the samples smoother and flatter, and it also improved the microstructural homogeneity. The microstructure was mainly composed of columnar dendrites, and most of ZrO₂ particles were located in the intergranular regions. The principal phase constituents were found to contain γ-Ni and t-NiZr₂, and the amorphous (Ni, Zr) intermetallic phase generated, because of more rapid solidification after ultrasound assisted. The microhardness was improved slightly with the increase of ZrO₂ contents, rising from 407.9 HV (10% ZrO₂) to 420.4 HV (30% ZrO₂). Correspondingly, wear mass loss was decreased with the maximum drop 22.7% of 30% ZrO₂ compared to that of 10% ZrO₂, and wear mechanisms were mainly abrasive wear with slightly adhesive wear. After applying ultrasound, the oxide islands in samples disappeared, and more ceramic particles were retained. Thus, the hardness and wear performance of the samples were improved.