Synthesis of B₄C, Al₂O₃, and AlB₁₂ reinforced Al matrix nano composites via mechanochemical method

Abstract

In this study, mechanochemical reactions in the ternary system of Al–B2O3–C were investigated. The starting materials were activated in a planetary ball mill under Argon atmosphere at different times. X-Ray diffraction and scanning electron microscopy (SEM) methods were used to characterize the products. The results showed that B4C, AlB12, and Al2O3 were formed at least after 4 h of milling. Furthermore, an aluminum borate (9Al2O3.2 B2O3) compound was formed during an aluminothermic reaction, as a by-product that could be diminished substantially by increasing the milling time to 20 h. SEM and TEM micrograph showed that the products were agglomerated and the range of particle size was within 100 nm. A high hardness value of 88 BHN with a compaction strength of 313 MPa can be achieved for the bulk sample sintered at 560°C for 90 min.

Study of Thermomechanical Properties of an Al‐Zn‐Based Composite Reinforced with Dodecaboride Particles

“…Moreover, as expected, after the annealing, that is, at room temperature, the composites' hardness increased with higher particle volume fractions. Such hardness improvement results from effective load transfer between the aluminum matrix and the reinforced AlB 12 particles, as previously demonstrated in aluminum-based composites containing B 4 C particles [15,16]. AlB 12 particles tend to organize themselves in clusters when surrounded by liquid aluminum, as indicated in previous works, attributed to the lack of sufficient mixing (stirring) when the matrix was molten [17].…”

Fabrication and characterization of nanoparticle MgO/B4C composite by mechanochemical method

“…Accumulation of the defects (gaps, dislocations, and grain boundaries) with the effect of mechanical activation of Mg start in the hexagonal closed packed structure increased the stress in the lattice, arranged the microstructural properties and the distribution of particles and the formation of new surfaces during milling process and shortened the diffusion distances. 31…”

“…Accumulation of the defects (gaps, dislocations, and grain boundaries) with the effect of mechanical activation of Mg start in the hexagonal closed packed structure increased the stress in the lattice, arranged the microstructural properties and the distribution of particles and the formation of new surfaces during milling process and shortened the diffusion distances. 31 When the SEM images of the synthesized powder mixtures at the end of 2, 4, and 6 h were examined (Figure 4(b) to (d)), it was determined that traces of mechanical and chemical effects were determined depending on the transformation in accordance with the microstructural and XRD analyses (Figure 2(c)) on behalf of the mechanochemical synthesis at the specified times. At the end of 6 h, stages of flattening of Mg powder particles, the increase in diffraction tendency, and reducing in crystalline size occurred as a result of deformation hardness.…”

Friction and wear properties of spark-plasma-sintered α-AlB12 and SiB6 powder compacts in water

“…Also, the α-AlB 12 -and SiB 6 -based ceramic disk specimens in our study exhibited specific wear rates as low as 3.0 Â 10 À 6 mm 3 /N m. It is considered that the low friction coefficients of the α-AlB 12 -and SiB 6 -based ceramic disk specimens were due to the formation of low friction H 3 BO 3 and Al(OH) 3 films with layered crystal structures [6] and low friction Si(OH) 4 gels on the worn surfaces. On the other hand, it is considered that the low specific wear rates of the α-AlB 12 -and SiB 6 -based ceramic disk specimens were due to their hardness higher than that of Si 3 N 4 and Al 2 O 3 [7][8][9][10][11].…”