Effect of Processing on Mechanically Alloyed and Spark Plasma Sintered Al‐Al₂O₃ Nanocomposites

Abstract

Metal matrix nanocomposites are advanced materials developed using ceramic nanoreinforcements and nanocrystalline metal matrices. These composites have outstanding properties and high potential for large number of functional and structural applications. In this work, nanocrystalline aluminium and Al-Al2O3nanocomposites were synthesised using mechanical alloying and consolidated through spark plasma sintering technique. Scanning electron microscopy, X-ray diffraction, and mapping were used to characterize the powders and sintered samples. Density and hardness of sintered samples were measured using densimeter and hardness tester, respectively. It was found that milling of pure aluminium for 24 h reduced its crystallite size to less than 100 nm. For Al-Al2O3nanocomposites, milling for 24 h decreased the crystallite size of the aluminium phase and resulted in uniform dispersion of the reinforcement. Sintering of the synthesised powders led to grain growth. Al2O3contributed to growth inhibition when samples were sintered for 20 minutes and improved the hardness but reduced densification. The Al-10 vol.% Al2O3nanocomposite had the highest Vickers hardness value of 1460 MPa.

Compressive strength and thermal properties of spark plasma sintered Al-Al2O3 nanocomposite

“…Al 2 O 3 nanocomposite had the highest Vickers hardness value of 1460 MPa. [3]. The effects of SPS on the structure, microhardness, and strength of AlMg5 monolithic alloy and AlMg5-0.4Al 2 O 3 composite were reported in a recent study [25].…”

“…The porosity of the composites was in the range 1.27 % to 5.07 %. In a recent work [3], Saheb at al. successfully synthesized nanocrystalline aluminum and homogenous Al-Al 2 O 3 nanocomposites using BM and SPS techniques and investigated the influence of reinforcement content, milling and sintering conditions, on the microstructure, densification, and hardness of the developed materials.…”

“…for various applications in the aerospace, automotive, and transportation industries. These materials consist of a ductile metal matrix reinforced with a hard and stiff ceramic phase [1][2][3][4]. The design goal for the development of these composites is to obtain materials with improved mechanical and/or functional properties.…”

“…Furthermore, the process is binder-less, direct, and cost-effective compared to other powder metallurgy processes. The SPS process was used to consolidate submicron and nanostructured aluminum [16][17][18][19], nanocrystalline aluminum alloys [20][21][22], and Al-Al 2 O 3 [3,[23][24][25] nanocomposites.…”

Electron backscattered diffraction analysis of friction stir processed nanocomposites produced via spark plasma sintering

“…Maximum temperature has a direct influence on the sintered materials density (Saheb, ). Normally, with the same temperature and pressure an increase in density and hardness is recorded for SPSed Al‐based materials (Liu et al ., ; Milligan et al ., ; Saheb et al ., ).…”