912 ISSN 1063-7850, Technical Physics Letters, 2018, Vol. 44, No. 10, pp. 912–915. © Pleiades Publishing, Ltd., 2018. Original Russian Text © A.P. Khrustalyov, G.V. Garkushin, I.A. Zhukov, S.V. Razorenov, 2018, published in Pis’ma v Zhurnal Tekhnicheskoi Fiziki, 2018, Vol. 44, No. 20, pp. 20–28. The Influence of the Structure of a Magnesium–Aluminum Nitride Metal-Matrix Composite on the Resistance to Deformation under Quasi-Static and Dynamic Loading A. P. Khrustalyov a *, G. V. Garkushin a, b , I. A. Zhukov a , and S. V. Razorenov a, b a Tomsk State University, Tomsk, 634050 Russia b Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow oblast, 142432 Russia *e-mail: tofik0014@mail.ru Received May 11, 2018 Abstract—The microstructure of an ML5 commercial magnesium alloy reinforced by aluminum nitride (AlN) nanoparticles with an average size of 80 nm at an amount of 0.5 wt % has been studied. Comparative data on strength and plasticity of the initial ML15 alloy and AlN-reinforced metal-matrix composite were obtained using Instron 3369 universal testing machine. The inf luence of material microstructure on the resis- tance of samples to high-rate deformation and fracture was determined by analysis of the full wave profiles measured using a VISAR laser Doppler velocimeter. DOI: 10.1134/S1063785018100255 Light-weight metal-matrix composites (MMCs) reinforced by dispersed particles have been extensively studied due to their unique combination of properties, including high specific rigidity and strength, as well as fracture toughness and so on. [1, 2]. It is also of inter- est to study the laws governing the elastoplastic and strength characteristics of MMCs based on cast mag- nesium alloys reinforced by AlN nanoparticles as manifested under conditions of quasi-static and shock-wave loading and fracture. The relative contri- butions of the internal structure factors to MMC resis- tance to deformation can be experimentally revealed by varying the material structure [3–6]. We have studied NNCs based on cast ML5 magne- sium alloy (matrix) reinforced by dispersed aluminum nitride nanoparticles, referred to below as ML5/AlN composite. AlN nanoparticles (with dimensions below 100 nm) were synthesized using the method of electri- cal explosion of wires [7]. ML5/AlN composite sam- ples were obtained by casting under a protective flux. Preliminarily prepared ML5 alloy melt (10 kg) heated to 710°C was charged into a special shank and stirred for 15 s. Then, 0.5 wt % AlN powder was introduced with continuous stirring for 1 min at 500 rpm by an original stirrer made of VT1 titanium alloy [8, 9]. Finally, the melt was cast into a 700 × 250-mm mold and vibration-treated during crystallization. An analo- gous procedure (melting, stirring, casting, and vibra- tion treatment until complete crystallization) was used for the preparation of pure ML5 alloy without intro- duction of nanoparticles. The samples of ML5 alloy and ML5/AlN compos- ite were characterized by (i) Rockwell hardness (HRF) measured on a TN-300 tester with a 1.6-mm diameter steel ball indenter at a 0.6-kN load applied for a 3-s dwell time, (ii) longitudinal sound velocity c l , and (iii) density ρ 0 . The microstructure of samples was studied using an Olympus GX71 optical microscope. The ten- sile strength under quasi-static axial loading was mea- sured on an Instron 3369 universal testing machine at 2 × 10 –4 s –1 strain rate. The samples for tensile testing were shaped as flat dumbbells with 40 × 8 × 1-mm working part dimensions. The accuracy of measure- ments was about 0.5% of the load. Table 1 presents generalized experimental data on the samples, includ- ing results of mechanical testing. Figures 1a and 1b present images of the structure of samples. Microstructure of the initial ML5 alloy com- prises equiaxial grains with dimensions d 0 ranging from 400 to 800 μm and an average grain size d 0 ~ 610 μm. The introduction of 0.5 wt % AlN nanoparti- cles led to the formation of a more uniform micro- structure of ML5/AlN metal-matrix composite with Table 1. Experimental data for ML5 alloy and ML5/AlN composite Material ρ 0 , g/cm 3 d 0 , μm σ 0.2 , MPa σ u , MPa δ, % HRF c l , m/s ML5 1.80 ± 0.02 610 55 122 4 62.2 5767 ML5/AlN 1.80 ± 0.02 420 70 155 5.5 62.6 5771