Development of NiTi and SiC h BN reinforced Al7075 composite via ultrasonic assisted squeeze casting route

Abstract

A17075 alloy has potential applications in aeronautics due to its high strength to weight ratio. During severe service environments, the A17075 alloy undergoes wear and corrosion. Another challenging aspect is the achievement of isotropic mechanical properties in A17075 alloy. Various A17075 composites were developed with improved mechanical, tribological, and tribocorrosion resistant properties to overcome these challenges. To date, various techniques viz. stir casting, squeeze casting, additive manufacturing, and powder metallurgy was used to fabricate a wide range of Al composites. Nevertheless, ultrasonic-assisted squeeze casting is a new method of achieving homogenous embedding of reinforcements that has not been fully explored. In the current study, a combination of tribocorrosion and wear-resistant reinforcements were opted for fabricating the A17075 composite. Two different A17075 composites were developed through ultrasonic aided high-pressure squeeze casting route A17075 (NiTiISiC) and A17075 (NiTi/h-BN). Further, the fabricated composite had undergone mechanical, metallurgical, tribocorrosion, and tribological characterizations. From the textural analysis, it had been observed that the addition of Ti had promoted grain refinement, which had improved the microhardness and yield strength in both cases. The A17075 (NiTi/h-BN) had outperformed an excellent microhardness and tensile strength of 123.1 HV and 343 MPa whereas, A17075 (NiTi/SiC) had showcased a lower microhardness and tensile strength of 119.2 HV and 334 MPa slightly. newlineInterestingly both the composites were observed with lt111gt texture. This facilitated the activation of octahedral slip planes resulting in improved tensile strength with isotropic mechanical properties. Further, the tribological investigation delineated that both the composites were immune to wear by exhibiting the least friction coefficient in the range of (0.2 to 0.23). newline