The American Society for Testing and Materials (ASTM) is an independent organization devoted to the development of standards.

American Society for Testing and Materials

Mechanically alloyed nanocomposites

Boron carbide is a strategic material, finding applications in nuclear industry, armour for personnel and vehicle safety, rocket propellant, etc. Its high hardness makes it suitable for grinding and cutting tools, ceramic bearing, wire drawing dies, etc. Boron carbide is commercially produced either by carbothermic reduction of boric acid in electric furnaces or by magnesiothermy in presence of carbon. Since many specialty applications of boron carbide require dense bodies, its densification is of great importance. Hot pressing and hot isostatic pressing are the main processes employed for densification. In the recent past, various researchers have made attempts to improve the existing methods and also invent new processes for synthesis and consolidation of boron carbide. All the techniques on synthesis and consolidation of boron carbide are discussed in detail and critically reviewed.

Synthesis and consolidation of boron carbide: a review

https://profdoc.um.ac.ir/articles/a/1023120.pdf

Comparison of microstructure and mechanical properties of A356 aluminum alloy/Al2O3 composites fabricated by stir and compo-casting processes

There are several modeling methods available for predicting the strength of metal matrix nanocomposites Among these, Zhang and Chen approach and Clyne method predict closer results to experimental values However, in Zhang and Chen method, the effect of Hall–Petch strengthening is neglected which results in less precision of the results In this study, the effects of all active strengthening mechanisms including Hall–Petch, Orowan, CTE mismatch and load bearing are considered, by using Clyne approach The results are in good agreement with experimental data and more precise than those from other models Furthermore, studies on different strengthening mechanisms showed that Hall–Petch strengthening mechanism is the most important factor, which should not be neglected even in micro-scale grain size

Comparison between current models for the strength of particulate-reinforced metal matrix nanocomposites with emphasis on consideration of Hall–Petch effect

In this study, a new method was used in stir casting to fabricate nano-Al2O3 particulate reinforced aluminum composites and avoid agglomeration and segregation of particles. Different volume fractions of nano-alumina particles were incorporated into the A356 aluminum alloy by a mechanical stirrer and then cylindrical specimens were cast and tested. The microstructural characterization of the composite samples showed uniform distribution of reinforcement, grain refinement of aluminum matrix, and presence of the minimal porosity. The effects of nano-Al2O3 particle content on the mechanical properties of the composites were investigated. Based on experiments, it was revealed that the presence of nano-Al2O3 reinforcement led to significant improvement in hardness, 0.2% yield strength, UTS and ductility. This combination of enhancement in UTS and ductility exhibited by nano-Al2O3 reinforced aluminum is due to uniform distribution of reinforcement and grain refinement of aluminum matrix.

Hamid Reza Baharvandi

Papers

Development of high-performance A356/nano-Al2O3 composites

The effect of particle size, sintering temperature and sintering time on the properties of Al–Al2O3 composites, made by powder metallurgy

Tensile and fracture behavior of nano/micro TiB2 particle reinforced casting A356 aluminum alloy composites

Microstructure and mechanical properties of aluminum alloy matrix composite reinforced with nano-particle MgO

Dry sliding tribological behavior and mechanical properties of Al2024–5 wt.%B4C nanocomposite produced by mechanical milling and hot extrusion