Materials Science and Engineering A 425 (2006) 145–155 Effect of strain rate on the compressive mechanical behavior of a continuous alumina fiber reinforced ZE41A magnesium alloy based composite M. G ¨ uden a,b,∗ , O. Akil a , A. Tasdemirci a , M. C ¸ iftc ¸ioglu b , I.W. Hall c a Mechanical Engineering Department, ˙ Izmir Institute of Technology, ˙ Izmir, Turkey b Materials Science and Engineering Program, ˙ Izmir Institute of Technology, ˙ Izmir, Turkey c Mechanical Engineering Department, University of Delaware, Newark, DE, USA Received 2 January 2006; received in revised form 14 March 2006; accepted 16 March 2006 Abstract The compressive mechanical response of an FP TM continuous fiber (35 vol.%) Mg composite has been determined in the transverse and longitudinal directions at quasi-static and high strain rates. It was found that the composite in the transverse direction exhibited strain rate sensitivity of the flow stress and maximum stress within the studied strain-rate range of 1.3 × 10 -4 to 1550 s -1 . The failure strain in this direction, however, decreased with increasing strain rate. Microscopic observations on the failed samples have shown that the composite failed by shear banding along the diagonal axis, 45 ◦ to the loading axis. Twinning was observed in the deformed cross-sections of the samples particularly in and near the shear band region. The strain rate sensitivity of the fracture stress of the composite in transverse direction is attributed to the matrix strain rate sensitivity. In the longitudinal direction, the composite failed by kink formation at quasi-static strain rates, while kinking and splitting were observed at the high strain rates. The maximum stress in the longitudinal direction was, however, found to be strain rate insensitive within the strain rate regime of 1.3 × 10 -4 to 500 s -1 . In this direction, similar to transverse direction, twinning was observed in the highly deformed kink region. Several different reasons are proposed for the strain rate insensitive compressive strength in this direction. © 2006 Elsevier B.V. All rights reserved. Keywords: Magnesium; Composite; Compression; High strain rate 1. Introduction Compared to their monolithic alloy counterparts, metal matrix composites (MMCs) usually provide higher strength and modulus, enhanced high temperature strength and wear resistance. Despite the high manufacturing costs, their outstand- ing thermo-mechanical properties make MMCs suitable mate- rials for aerospace, defense and automobile industries where improved material performance may outweigh the cost penalty. Dynamic loading response is an important design parameter, which is critical in severe applications where impact loading occurs. Under impact conditions, the strain rate in the composite may locally reach strain rates in excess of 1000 s -1 . Therefore, high strain-rate mechanical response of MMCs is important in present and future applications in these industries. ∗ Corresponding author. Tel.: +90 232 7506595; fax: +90 232 7506505. E-mail address: mustafaguden@iyte.edu.tr (M. G¨ uden). Previous studies on high strain rate deformation behavior of MMCs mostly concentrated on particulate, short fiber and whisker reinforced MMCs [1–7], groups of MMCs having wider application fields. Few studies have been conducted on the high strain-rate response of continuous fiber reinforced MMCs and these were mainly on Al matrix composites [8–11]. Being the lightest common structural metal, Mg can potentially provide a high strength to weight ratio which is important in applications where weight saving is an important design criterion. Despite the many experimental investigations conducted to understand the deformation behavior and mechanical properties of magnesium metal matrix composites and unreinforced alloys at quasi-static strain rates, the mechanical properties of Mg based MMCs and unreinforced alloys at increasing strain rates have not been inves- tigated as much. Klimanek and P¨ otzsch [12] investigated the microstructural evolution of pure magnesium under compression at different strain rates between 10 -3 and 500 s -1 at room temperature and 150 ◦ C. Flow stress increased with decreasing temperature and 0921-5093/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.msea.2006.03.028