Microstructure and wear resistance of laser melting deposited NiTi/Ni₃Ti intermetallic alloys

The wear-resistant NiTi/Ni₃Ti intermetallic alloys were designed and fabricated by the laser melting deposition process. The as-solidified microstructures of the NiTi/Ni₃Ti intermetallic alloys were characterized by X-ray diffraction (XRD), optical microscope (OM), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The wear resistance of the alloys was evaluated under room-temperature dry sliding wear test condition coupling with hardened bearing steel GCr15. The results indicate that the room temperature dry-sliding wear mechanism of the NiTi/Ni₃Ti intermetallic alloy with NiTi dendrite as the primary phase is soft abrasion and oxidative wear, while that of the NiTi/Ni₃ Ti intermetallic alloy with Ni₃Ti as the primary phase is oxidative wear and micro-cutting under low/medium normal load, and micro-cutting is under high normal load; the NiTi/Ni₃Ti intermetallic alloy with NiTi dendrite as the primary phase has better wear resistance under dry sliding wear test conditions than that with Ni₃Ti as the primary phase.