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Grain size control of any engineering metal is very important in the hot upsetting process. Generally, the grain size directly controls the mechanical properties and performance of the material. Al–B4C composite finds extensive applications in nuclear industries, defense, and electronic industries. Therefore, the aim of this work is to study the dynamic recrystallization (DRX) behavior of Al–4 wt % B4C composite during the hot upsetting test. Experimental work was performed on sintered Al–4 wt % B4C preforms at various initial relative density (IRD) values of 80%, 85%, and 90%, and over the temperature range of 300–500 °C and strain rates range of 0.1–0.3 s−1. The DRXed grain size of Al–4 wt % B4C preforms for IRDes, and temperatures and strain rates were evaluated by using an optical microscope. The activation energy (Q) and Zener–Hollomon parameter of sintered Al–4 wt % B4C preforms were calculated for various deformation conditions and IRDes. The mathematical models of DRX were developed as a function of Zener–Hollomon parameter for various IRDes to predict the DRXed grain size. It was found that the DRXed grain size decreases with increasing Zener–Hollomon parameter. Verification tests were done between the measured and predicted DRXed grain size for various IRDes, and absolute and mean absolute error was found to be 9.92% and 8.58%, respectively.

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Aluminum-based metal matrix composites with single or multiple ceramic reinforcements are finding application in the aerospace and automobile industries. In this research work, novel AA7150-B4C (aluminium7150 alloy–Boron carbide) nanocomposites were successfully fabricated, through the liquid metallurgy route via stir casting method, with the incorporation of B4C nanoparticles with different weight percentages using a novel sequence of a vortex technique and a double stir casting process with ultrasonication. The formed composites have been thoroughly studied for microstructure refinement, nano-particulate distribution, and bonding with the matrix by making use of the optical microscopy (OM) and scanning electron microscopy (SEM) studies (respectively). In addition, the composites were analyzed for the density, porosity, and elemental composition. Further, the composites were tested for the investigation of mechanical properties, like micro-hardness and tensile strength, to investigate the influence of ultrasonic vibration on the arrangement of B4C nano-particulates. The analysis indicated that the mechanical properties of the AA7150-B4C nanocomposites in as-cast condition significantly improved with a gain of 57.7% in strength and 24.5% in hardness compared to the native AA7150 material.