Effect of chemical composition on the intermetallic compound formations of cold-sprayed Ni-Ti composite coatings

Cold gas dynamic spraying (CS) is a consolidating method to obtain surface coatings on a wide verity of substrates. In this method, coating deposition relies on kinetic rather than thermal energy which makes it possible to spray mixtures of different material powder including low and high-temperature melting materials and ceramics and metal mixtures. In this research, cold spraying of composite Ni-Ti coating and formation of intermetallics after post spray heat-treatment were investigated. Physically blended gas atomized Ni and Ti powders mixtures with equivalent atomic, volume and optimized ratios (respectively with 55, 61.3 and 75.4 % at Ni and balanced Ti ratios) were sprayed as the feedstock powders on titanium and stainless steel substrates. High-density composite coatings with well dispersed Ni and Ti particles were achieved. The chemical compositions of the composite coatings were evaluated using EDS analysis and 10.5, 35.2 and 55 at. % Ni (and with balanced Ti ratios) compositions were obtained for three composite coatings. PSHT were conducted at 900 ̊C for 60 minutes and comparative studies on the intermetallic compound formations were carried out. Microstructural investigation showed that all three equilibrium intermetallics of binary Ni-Ti phase diagram including Ni3Ti, Ti2Ni and NiTi phases were formed at two Ni rich composite coatings while the other coating appeared to have only Ti2Ni phase.

کلیدواژه ها:

Cold spray ، Composite Coating ، Ni-Ti ، Intermetallic ، Composition