Fabrication and characterization of an Al-based nanocomposite with high specific strength and good elongation using large amount CMA nanoparticles Hossein Ramezanalizadeh Department of Materials and Polymer Engineering, Faculty of Engineering, Hakim Sabzevari University, P.O. Box 397, Sabzevar, Iran article info Article history: Received 28 October 2019 Received in revised form 2 January 2020 Accepted 3 January 2020 Available online 5 January 2020 Keywords: Aluminum matrix nanocomposites Mechanical properties Mechanical milling/alloying Microstructure Interfaces abstract In the present research, preparation and characterization of both powder and bulk of a new Al-CMA nanocomposite were investigated. For this, the composites were prepared by mechanical alloying/ milling (MA/MM) of 10 wt % Al 3 Mg 2 and pure Al mix powders and then cold pressing, sintering and finally hot extrusion. According to the microscopic observations, a uniform distribution of Al 3 Mg 2 in the Al and a clean interface between them were obtained after ball milling. In addition, analysis of particle size distribution revealed that the presence of Al 3 Mg 2 particles and amount of process control agent had a significant influence on the composite powder refinement. In addition, the measured Carr index of 13.5% indicated that the ball milled powder offered good flowability. High-resolution microscopic studies showed that formation of twins might be one of the crystallite size decreasing mechanisms during MA/ MM process. The initial powder boundary in the powder samples could not be completely deleted by cold pressing and sintering, but could be reduced by following hot extrusion. The microstructure of extruded nanocomposites comprised nanometer Al grains and Al 3 Mg 2 nanoparticles dispersed interior grains which produced by dynamic recrystallizations (DRX). The Al 3 Mg 2 particles experienced vigorous size reduction during MA/MM, which play an important role in Al grain refining during DRX via Zener pinning. These conditions along with clean interface for the 15 h milled sample could be resulted in notable enhancement of 515% in yield strength (YS), 603% in ultimate compressive strength (UCS), 181% in young’s modulus and 406% in microhardness compared with pure Al. A more interesting point was the elongation up to 24% owing to the uniform distribution of nanoparticles in Al grains. These results from AleAl 3 Mg 2 nanocomposites discover newer feasibilities for impressive manufacturing of high strength and low-density composites with improved ductility, which could make them possible candidates for a wide range of industries especially for weight critical applications. © 2020 Elsevier B.V. All rights reserved. 1. Introduction Recently, much research work has been focused on synthesizing the composite materials because of unique combination of prop- erties unachievable with conventional materials [1]. Amongst the metal matrix composites (MMCs), Al-based matrix composites (AMCs) attract the most attention owing to their low density, high specific strength and stiffness, excellent wear resistance etc [2]. On the other hand, metal matrix nanocomposites (MMNCs) are most promising in producing balanced mechanical properties between nano- and micro-structured materials, i.e., enhanced hardness, Young’s modulus, 0.2% yield strength, ultimate tensile strength and ductility, due to the addition of nanosized reinforcing particles into the matrix [3]. The large ductility of the Al-based matrix and the high strength of the hard reinforcements are two interesting features of AMCs. Three key factors should be considered in selection of the second phases: low density, high stiffness and good wettability between the matrix and second phase. Ceramics in the form of particles such as Al 2 O 3 , SiC, B 4 C, AlN, TiC, TiO 2 TiB 2 and CNT [4,5], flakes or fibers, are the most common reinforcements that used in usual AMCs. Besides the high stiffness and reasonable density, ceramic materials show low wettability with the Al-based matrix that leads to par- ticles clustering, porosity and damaging interfacial reactions. Although, using a metal layers as a coat on the reinforcement E-mail addresses: h.ramezanalizadeh@hsu.ac.ir, hralizadeh@ut.ac.ir. Contents lists available at ScienceDirect Journal of Alloys and Compounds journal homepage: http://www.elsevier.com/locate/jalcom https://doi.org/10.1016/j.jallcom.2020.153667 0925-8388/© 2020 Elsevier B.V. All rights reserved. Journal of Alloys and Compounds 822 (2020) 153667