Development of high performance Mg–Al₂O₃composites containing Al₂O₃in submicron length scale using microwave assisted rapid sintering

Abstract

In the present study, magnesium composites reinforced with different volume fraction of submicron size Al 2 O 3 particulates were synthesised using powder metallurgy technique incorporating an innovative microwave assisted rapid sintering technique. The sintered materials were subsequently hot extruded for characterisation in terms of microstructural, physical and mechanical properties. Microstructural characterisation results revealed a reasonably uniform distribution of Al 2 O 3 particulates, minimal porosity and good matrix reinforcement interfacial integrity. The average coefficient of thermal expansion (CTE) value for Mg-Al 2 O 3 composites was found to decrease with increasing amount of submicron Al 2 O 3 particulates. Mechanical characterisation of the composites revealed an increase in hardness, elastic modulus, 0 . 2% YS and ultimate tensile strength (UTS) with the increase in amount of alumina particulates. Ductility exhibited the reverse trend. An attempt is made in the present study to correlate the effect of the presence of submicron alumina and its increasing amount with the microstructural, physical and mechanical properties of magnesium.

Direct laser sintered WC-10Co/Cu nanocomposites

“…10) leads to a significant reduction in the coefficient of thermal expansion (CTE) of the Cu matrix (CTE value: WC 6.0 Â 10 À6 K À1 versus Cu 17.0 Â 10 À6 K À1 [29]). In other words, the nanostructured reinforcement possesses a more effective ability to constrain the expansion of the matrix [30,31], thereby favoring the formation of coherent particulate/ matrix interfaces (Fig. 10).…”

Particle-Reinforced Cu Matrix Composites by Direct Metal Laser Sintering (DMLS) Additive Manufacturing (AM): Interface Design, Material Optimization, and Process Control

“…Gåård et al's work [13] confirms that the stress in composites is developed as a consequence of internal constraints caused by different CTE of various phases. According to the Turner model [25], the average CTE, α t , of multiphase materials can be calculated by the following equation:…”

Enhancing the Mechanical Response of a Lead-Free Solder Using an Energy-Efficient Microwave Sintering Route

“…Some of the compacted billets were sintered using an innovative microwave-assisted hybrid sintering technique for 6 min and 45 s to reach a temperature of 221°C under ambient conditions in a 900 W, 2.45 GHz SHARP microwave oven using SiC as the microwave susceptor material. 11,12,15,16 The set time included only heating time and there was no holding time to minimize or eliminate bulk and/or localized melting of samples. SiC powder (contained within a microwave-transparent ceramic crucible) absorbs microwave energy readily at room temperature and is heated quickly, providing the radiant heat to heat the billet externally while the compacted billet absorbs microwaves and is heated from within.…”

“…17 To eliminate the drawbacks of these two conventional methods, bidirectional rapid microwave sintering has been used. 11,12,15,16 The result of an open literature search indicates that no research attempt has yet been made to process Sn-3.5Ag using the technique of powder metallurgy particularly adopting bidirectional microwave sintering process.…”

“…Sintering can be done by traditional methods of heating such as resistance heating 6,7 or by the more recently introduced method of using microwaves. [8][9][10][11][12][13][14][15][16] In a typical resistance heating furnace, the direction of heating is from the outside to the inside of the powder compact, while for microwaves the direction of heating is from the inside to the outside. The former results in poor microstructural characteristics in the core of the powder compact while the latter results in poor microstructural characteristics of the surface.…”