The effect of particle size on microstructure, relative density and indentation load of Mg-B₄C composites fabricated at different loading rates

Abstract

The effect of reinforcing particle size on microstructure, relative density and indentation of Mg reinforced by 0, 1.5, 3, 5 and 10% volume fractions of nano- and micro-sized B4C was investigated. The composites were fabricated through powder compaction technique at strain rates of 1.6 × 103 s−1, 8 × 102 s−1 and 8×103 s−1 using split Hopkinson bar, drop hammer and Instron, respectively. The results indicated that the size of B4C and loading rate had significant effect on relative density. For example, the relative density of Mg-10 vol.% B4C nanocomposite was around 2.5% higher than that of its corresponding microcomposites. The relative density of the samples produced at high rate of loading was in average 1.2% higher than that of the samples fabricated quasi-statically. The results of indentation tests on the produced nanocomposite and microcomposite samples also revealed that loading rate and B4C particle size had significant effect on strength of specimens. For example, for Mg-5 vol.% B4C, the maximum load in load–depth curve of the specimens produced by split Hopkinson bar increased from 530 N for micron-sized B4C to 780 N for nano-sized B4C, around 45% improvement. Moreover, nanocomposites had better indentation resistance compared to similar micro composites fabricated using the three methods.

Influence of microwave sintering temperatures on mechanical and microstructural Behavior of Al/SiC/snail shell hybrid composite synthesized through powder metallurgy technique

“…A quasi-static pressure of 600 MPa was applied in this study to produce the high-densified composite with minimum porosity levels. 36 Figure 8 represents the variation in porosity for the conventional sintered composite at different wt % SiC reinforcements. The theoretical density of the Al-SiC was found to be enhanced from 2.72 to 2.76 g/ cm 3 with the addition of SiC particles from 2 wt% to 10 wt% due to the increase in the incorporation of the high-density SiC particles (Refer Figure 8(a)).…”

Effect of Variations in Microwave Processing Temperatures on Microstructural and Mechanical Properties of AA7075/SiC/Graphite Hybrid Composite Fabricated by Powder Metallurgy Techniques

“…Notably, the high compaction pressures at low rates (quasi static compaction) reduces the porosity levels in the materials as compared to high compaction rates (dynamic compaction) [19]. In order to minimize the porosity levels, in this present work, a high compaction pressure of 600 MPa was applied at low compaction rates [41]. Figure 5 demonstrates the porosity levels of the fabricated composite sintered through different sintering mechanisms.…”

Archives of Metallurgy and Materials

“…these air gaps obstruct the heat transfer during the sintering and lead to improper sintering of the composite [26]. the porosity of a given specimen depends on the magnitude of pressure applied during the compaction stage and the densification behaviour of the as-received powders [27]. in the quasi-static condition of the compaction process, the particles have sufficient time to move and occupy the void spaces to produce the densified composite.…”