Aluminium hybrid composites are a new generation of metal matrix composites that have the potentials of satisfying the recent demands of advanced engineering applications. These demands are met due to improved mechanical properties, amenability to conventional processing technique and possibility of reducing production cost of aluminium hybrid composites. The performance of these materials is mostly dependent on selecting the right combination of reinforcing materials since some of the processing parameters are associated with the reinforcing particulates. A few combinations of reinforcing particulates have been conceptualized in the design of aluminium hybrid composites. This paper attempts to review the different combination of reinforcing materials used in the processing of hybrid aluminium matrix composites and how it affects the mechanical, corrosion and wear performance of the materials. The major techniques for fabricating these materials are briefly discussed and research areas for further improvement on aluminium hybrid composites are suggested

This paper reviews from the corpus of literatures on high-entropy alloys (HEAs), their mechanical and corrosion behavior as affected by metallurgical factors such as processing technique, composition, phase formation and transition. HEAs are a promising class of alloys which are designed based on the use of multiple component alloying elements in equimolar or near equimolar ratio. There has been surging interest in this class of alloys on account of their unique property range. Their unique metallurgical characteristics, structures, mechanical and corrosion properties, current and potential areas of applications, and suggestions for future research are discussed in this paper

The mechanical properties of aluminium hybrid composites reinforced with groundnut shell ash (GSA) and silicon carbide was investigated. GSA and silicon carbide with different mix ratios (10:0, 7.5:2.5, 5.0:5.0, 2.5:7.5 and 0:10) constituted 6 and 10wt.% of the reinforcing phase, while the matrix material was Al–Mg–Si alloy. The hybrid composites were produced via a two-step stir casting technique. Microstructural examination, hardness, tensile and fracture toughness testing were carried out to appraise the mechanical properties of the composites. The results show that with increasing GSA in the reinforcing phase, the hardness, ultimate tensile strength (UTS) and specific strength of the composites decreased slightly for both 6 and 10wt.% reinforced Al–Mg–Si based composites owing to the amount of the oxides of Al, Si, Ca, K2 and Mg present in the composition of GSA. However, the percentage elongation improved marginally and was generally invariant to increasing GSA content while the fracture toughness increased with increasing GSA content. GSA offered a favourable influence on the mechanical properties of Al–Mg–Si hybrid composites comparable to that of rice husk ash and bamboo leaf ash

The high dependence on fossil fuels has escalated the challenges of greenhouse gas emissions and energy security. Biohydrogen is projected as a future alternative energy as a result of its non-polluting characteristics, high energy content (122 kJ/g), and economic feasibility. However, its industrial production has been hampered by several constraints such as low process yields and the formation of biohydrogen-competing reactions. This necessitates the search for other novel strategies to overcome this problem. Cell immobilization technology has been in existence for many decades and is widely used in various processes such as wastewater treatment, food technology, and pharmaceutical industry. In recent years, this technology has caught the attention of many researchers within the biohydrogen production field owing to its merits such as enhanced process yields, reduced microbial contamination, and improved homogeneity. In addition, the use of immobilization in biohydrogen production prevents washout of microbes, stabilizes the pH of the medium, and extends microbial activity during continuous processes. In this short review, an insight into the potential of cell immobilization is presented. A few immobilization techniques such as entrapment, adsorption, encapsulation, and synthetic polymers are discussed. In addition, the effects of process conditions on the performance of immobilized microbial cells during biohydrogen production are discussed. Finally, the review concludes with suggestions on improvement of cell immobilization technologies in biohydrogen production.

This paper presents an overview of the corrosion behavior of titanium (Ti) alloys in both acidic and saline solutions. The solutions covered in this review are essentially the typical electrolytes encountered by Ti alloys when applied under service conditions. Although Ti alloys are generally known to be corrosion resistant, this review identifies strong reducing acids and fluoride-containing solutions as electrolytes that corrode Ti and its alloys. The pathways that the knowledge of the corrosion behavior of Ti alloys have followed from the 1950s to date are captured in this review. Based on this, the different factors influencing the corrosion behavior of Ti alloys are highlighted and the different research concepts for improving the corrosion resistance of Ti alloys in both solutions are discussed. The limitations of these research concepts are mentioned and the directions for future research are proposed.