Heterostructured NiCrTi Alloy Prepared by Spark Plasma Sintering with Enhanced Mechanical Properties, Corrosion and Tribocorrosion Resistance

Abstract

Nickel-based alloys applied in marine environments often face multiple challenges of stress, corrosion and wear. In this work, heterostructured NiCrTi alloy was prepared by spark plasma sintering coarse Ni20Cr and ultrafine Ti powders. Apart that some are dissolved into the nickel alloy, Ti powders react in situ with Ni20Cr during sintering to form hard intermetallic Ni₃Ti. It builds up a typical heterostructure that endows NiCrTi alloy with well-balanced mechanical strength and plasticity, e.g. high yield strength of 1321 MPa, compressive strength of 2470 MPa, and compressive strain of 20%. On tribocorrosion, the hard shell enriched with Ti transforms to connected protrusion and form in situ surface texture. Oxides or wear debris are trapped at the textured surface and compacted to form a stable tribofilm. Thus negative synergy between corrosion and wear is observed for NiCrTi and high tribocorrosion resistance is achieved. At a potential of + 0.3 V, the tribocorrosion rate of NiCrTi is reduced by an order of magnitude to 1.87 × 10^− 5 mm³/(Nm) in comparison to the alloy Ni20Cr.