Development and characterization of in‐situ nickel aluminide reinforced Al‐Si matrix composites by stir casting

Abstract

Aluminium matrix composites (AMCs) exhibit promising mechanical properties that are required for the aeronautical and automotive industries. In the current research, A413 (eutectic AlSi) alloy is employed as matrix material, and nickel based trialuminide (Al3Ni) with primary Si particles as reinforcements to manufacture aluminium matrix composites through the stir casting process. A total of three varieties of composite alloys containing 3, 6, and 9 wt% of nickel were used to fabricate stir cast composites, and their microstructural features, along with mechanical properties, such as tensile strength, impact strength, and hardness, were evaluated. Furthermore, the dry sliding wear behavior for three different applied loads (10, 20, and 30 N) was studied. Scanning electron microscopy (SEM) revealed nucleation of Al3Ni nickel trialuminide and increase of primary Si phases as well as exhibited even dissemination of such reinforcements in α‐Al. The composite with the highest nickel content (9 wt%) had a microstructure that consisted of 31 vol% in‐situ Al3Ni intermetallic and 8.1 vol% primary Si particles. This composite demonstrated a maximum increase of 25.93% in hardness and 40.30% in tensile strength. The quality index values of composites with in‐situ reinforcements were higher compared to that of A413 alloy, which had the lowest quality index value of 248.83 MPa, representing a 9.91% decrease. The impact strength of the composite was found to be reduced by a maximum of 50% and showed a significant loss in ductility also when compared with A413 aluminium alloy. Wear resistance was found to be increased with the evolution of in‐situ reinforcements inside the matrix, whereas an increase in applied load resulted in a higher wear rate. The uniform dispersion and good interfacial bonding between the aluminium matrix and in‐situ reinforcements (nickel trialuminide and primary Si) are showing preeminent mechanical properties and can be a novel composite material for industrial applications.