Properties of AlN-Based Magnesium-Matrix Composites Produced by Pressureless Infiltration

Abstract

A novel ceramic-metal composite with continuous interconnected ceramic and metal phases has been fabricated from sintered porous particulate AlN preforms infiltrated with magnesium. The 48 vol. % AlN composites are fabricated by pressureless infiltration in argon in the temperature range of 870 °C to 960 °C. An increase in the infiltration rate is observed as the temperature increases. Results on the mechanical characterization of the composites indicate an elastic modulus of 90 to 110 GPa and hardness of 70 to 80 HRB. The tensile strength calculated by the shear punch test method ranges from 260 to 390 MPa. As a general rule, it is observed that the lower the infiltration temperature, the higher the tensile strength. The linear coefficient of thermal expansion of the infiltrated composites in the temperature range of 215 to 315 °C is 7.65 x 10-6 °C-1. This value is lower than those found for similar Al/AlN composites reported in the literature.

Progress in preparation of AlN-reinforced magnesium matrix composites: A review

“…3, and the infiltration can be either from the bottom up or in the direction of gravity. León et al [29] fabricated AlN/Mg composites via pressureless infiltration, with the AlN volume fraction reaching 48%. The Young's modulus of the composites was found to be between 90-110 GPa, while the tensile strength reached a maximum value of 390 MPa.…”

Nano-AlN particle reinforced Mg composites: Microstructural and mechanical properties

“…X-ray diffraction analysis was carried on the extruded Mg and Mg/AlN composite samples using automated Shimadzu LAB-X XRD-6000 diffractometer. Flat polished samples cut from the cross-section and longitudinal sections of the extruded rods of each composition were scanned at a scanning speed of 2u min 21 , with a scanning range of 20-80u. The plot of intensity against diffraction angle, 2h, where h is the Bragg angle, is plotted.…”

“…Heating rate of 5uC min 21 was maintained. Argon gas flowrate was maintained at 100 ccm min 21 . Displacement of the test samples (each 5 mm long) as a function of temperature (50-400uC) was measured using an alumina probe and was subsequently used to determine the CTE.…”

“…24 The tensile and compressive properties of the as extruded pure magnesium and its composite counterparts were determined using an MTS 810 automated servo hydraulic mechanical testing machine in accordance with the procedures outlined in ASTM standards E8/E8M-13a 25 and E9-09 26 respectively. The crosshead speed was set at 0?254 mm min 21 (strain rate: 0?010 min 21 ) and 0?04 mm min 21 (strain rate: 0?005 min 21 ) respectively. For each composition, a minimum of six tests were conducted to obtain repeatable values.…”

“…Leo ´n et al studied the properties of AlN based Mg-MMCs produced by pressure-less infiltration. 21 Using mechanical milling, Thein et al produced Mg-5 wt-%Al-x wt-%AlN composites. 22 Experimental findings of the above mentioned works clearly demonstrate AlN as a promising reinforcement in Mg and hence, an attempt is made in this study to investigate the effects on nanoscale AlN particles on the microstructural, thermal, indentation, tensile and compressive properties of monolithic Mg. Mg/AlN nanocomposites required for this study were produced using the blend press sinter based powder metallurgy technique as it is considered a reliable method to fabricate complex/unique shapes that are impractical by other processes.…”