Effect of Al Additions on the Microstructure and Mechanical Properties of the SHS Product of Ni-Al-TiO<sub>2 </sub>Mixtures

Intermetallics have attracted much interest in the high-temperature application. The Self-propagation High-temperature Synthesis (SHS) process offers an effective route to synthesize the intermetallic materials. However, an excessive composition of the SHS reactant can affect the structure and properties of the synthesized product. In this work, the SHS process was used to synthesize the mixture of Ni, Al, and TiO2 with different Al additions. The structure and properties of the product were characterized by SEM, EDS, and XRD tests. The mechanical properties of the product were evaluated by a Vickers microhardness test. The result shows that several intermetallic phases such as NiAl, TiNi, and TiAl were formed in the synthesized product. The formation of oxide appeared in the product due to the product reaction as well as the air environment. An increased Al addition resulted in decreased pores and increased hardness. The addition of 1.11 wt.% Al achieved the maximum hardness of the product. However, cracks were observed in the sample with the highest hardness. Excessive addition of Al decreased the hardness.

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