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A magnesium alloy was subjected to severe plastic deformation via an unconventional equal channel angular extrusion route at decreasing temperatures. This method facilitates incremental grain refinement and enhances formability by activating dynamic recrystallization in the initial steps and suppressing deformation twinning. Compression experiments in three orthogonal directions demonstrated high strength levels in the processed sample, up to 350 MPa in yield and 500 MPa in ultimate strengths. Notable flow stress anisotropy is correlated with the processing texture and microstructure.

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Aluminum metal matrix composites, which exhibit significantly high compressive strength, were produced through the squeeze casting process using aluminum 7075 alloy as the matrix material and 2.5 wt% alumina as reinforcement. The process parameters of squeeze casting were prudently selected based on the literature in order to obtain better mechanical properties such as compressive strength and hardness. Samples were examined using an optical microscope, energy dispersive spectroscopy, a scanning electron microscope, and X-ray diffraction analysis. The optical micrograph showed low porosity in the produced composite, which matched the porosity measured using the Archimedes principle. The scanning electron microscope showed uniform distribution of reinforcement in the grain boundaries of the matrix. An X-ray diffraction analysis confirmed the presence of Al 2 O 3 particles in the composite. The hardness of the composite improved from 44 to 59 HRB. The compressive strength of the composite improved significantly with the addition of alumina reinforcement to 587 MPa when compared to Al 7075 alloy as well as other aluminum metal matrix composites reported in the literature.

The microstructural evolution, tensile response and wear properties of a two-phase Zn – Al alloy (Zn-8 wt.% Al, ZA-8) have been studied after severe plastic deformation by equal channel angular extrusion (ECAE). The experimental results reveal that the strength levels of the ECAE processed samples were considerably improved regardless of the processing route. More importantly, the elongation at fracture was dramatically increased after ECAE. The optimum tensile properties (high strength and high ductility) were reached after eight ECAE passes following route BA. It was also found that the wear rate of severe plastically deformed ZA-8 is considerably lower than that of the as-cast alloy, especially under high applied pressures, demonstrating improved wear resistance of ZA-8. Moderate strength and high ductility along with improved wear resistance in the ECAE processed ZA-8 samples in comparison with the brittle as-cast alloy makes these alloys attractive for wear-sensitive structural applications.

In the present work, the influence of stirrer blade design on the dispersion of reinforcement particles in the aluminium metal matrix was studied extensively through experiments and also simulated them using Computational Fluid Dynamics (CFD) method. The microstructure and mechanical properties of the produced metal matrix composites (MMCs) was studied. The analysis of the microstructure was performed using an optical microscope to visualise the reinforcement distribution and binding within the matrix. Further the MMCs were also characterised by Field Emission Scanning Electron Microscope (FESEM) and X-ray Diffraction (XRD). The method of Archimedes is used to assess the experimental density and the theoretical density is determined using the mixture law to determine the percentage of porosity in the MMCs. Hardness, compression and tensile testing are performed on the produced samples. A three-dimensional computational method was used to predict the flow field of aluminium melt and study the influence of the blade design on the distribution of the reinforcement. Experimental results validated the CFD recommendation on the blade design. The CFD recommendation was based on the structure, power number and the number of blades and accordingly, the four-blade flat stirrer (B4) design was the best. The experimental results also corroborated the CFD recommendation with the four-blade flat stirrer design achieving the highest compressive strength (642 MPa), highest hardness (45 HRB), and highest tensile strength (206 MPa) among the five different blade designs investigated.