Corrosion and Wear Behaviour of Spark Plasma-Sintered NiCrCoAlTiW-Ta Superalloy
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NiCrCoAlTiW-Ta superalloy was sintered using spark plasma sintering technique. The influence of starting powder particle size on the corrosion and dry sliding wear behaviour of sintered NiCrCoAlTiW-Ta superalloy was investigated. The nickel matrix (> 60 wt%) was varied over three different particle sizes (3–44, 45–106 and 106–150 µm). The powders were sintered at 1100 °C, heating rate of 100 °C/min and pressure of 32 MPa. The effect of particle sizes on sintered density, microhardness, corrosion and wear were reported. The results show that the sintered density of 97.48% and microhardness value of 382.88 HV0.1 were reported for the smallest starting powder. Furthermore, the microstructures of the sintered alloy revealed the presence of three major phases: γ, γ′ and the precipitated solid solution phase. There was an improvement in the corrosion response in relation to the particle size of the starting powder. This indicates that the least corrosive alloy has the least starting powder particle size. It has a corrosion rate of 0.047 and 0.056 mm/year in saline and acidic media, respectively. Also, the coefficient of friction increased with increase in powder particle size. However, the poor wear response of the alloys with bigger powder particle size could be attributed to poor adhesion of the oxide layer.
KeywordsParticle size Superalloy Spark plasma sintering Corrosion Wear
This work is funded by the Research and Innovation Directorate of Tshwane University of Technology and supported, in part, by the Department of Mechanical Engineering, Mechatronics and Industrial Design, Institute for NanoEngineering Research (INER), Department of Chemical, Metallurgical and Materials Engineering and the Faculty of Engineering and Built Environment of the Tshwane University of Technology, Pretoria, South Africa.
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