Yaojun Lin

Spray Forming of MMCs

This article provides a comprehensive review on metal matrix composites (MMCs) produced via spray forming. First, the principles, characteristics, and applications of spray forming are presented, which is considered as a prerequisite to discuss spray forming of MMCs. Then, spray forming techniques in the fabrication of MMCs are systematically reviewed. Next, microstructural characteristics and physical/mechanical properties of spray-formed MMCs are described. Finally, the mechanisms involved during spray forming are analyzed.

Influence of Cr removal on the microstructure and mechanical behaviour of a high-entropy Al0.8Ti0.2CoNiFeCr alloy fabricated by powder metallurgy

ABSTRACT We report a systematic study on the influence of Cr removal on the microstructure and mechanical behaviour of an ultra-fine grained (UFG) high-entropy alloy (HEA), Al0.8Ti0.2CoNiFeCr, fabricated via spark plasma sintering (SPS) of mechanically alloyed (MA’ed) powders from constituent elemental powders. The MA’ed Al0.8Ti0.2CoNiFeCr powders consist principally of a BCC phase (∼85 vol.-%) with a small amount of FCC phase (∼15 vol.-%), whereas the MA’ed Al0.8Ti0.2CoNiFe powders present similar phases to those in the MA’ed Al0.8Ti0.2CoNiFeCr powders. Interestingly, the SPS processed UFG Al0.8Ti0.2CoNiFeCr alloy contains mostly an FCC phase (∼78 vol.-%) and some BCC phase (∼22 vol.-%); in contrast, the SPS processed UFG Al0.8Ti0.2CoNiFe alloy consists of a slightly enriched BCC phase (∼53 vol.-%) and an FCC phase (∼47 vol.-%). In addition, the SPS processed Al0.8Ti0.2CoNiFe alloy exhibits slightly higher yield strength, compressive strength and hardness but lower plasticity than those of the SPS processed Al0.8Ti0.2CoNiFeCr alloy. Special theme block on high entropy alloys, guest edited by Paula Alvaredo Olmos, Universidad Carlos III de Madrid, Spain, and Sheng Guo, Chalmers University, Gothenburg, Sweden.

4.13 Gradient Metal Matrix Composites

This chapter presents a comprehensive overview on gradient metal matrix composites (MMCs), including design, synthesis, microstructures, mechanical properties, and applications. First, design optimization of gradient MMCs using “reversal design” is explained. Second, various processing methods for the synthesis of gradient MMCs are described. Third, microstructures and mechanical properties of gradient MMCs are presented. Finally, the applications of gradient MMCs are reviewed.