The quasi-static and cyclic fatigue fracture behavior of 2014 aluminum alloy metal-matrix composites

  • PDF / 3,855,710 Bytes
  • 16 Pages / 612 x 792 pts (letter) Page_size
  • 68 Downloads / 204 Views

DOWNLOAD

REPORT


I. INTRODUCTION

DISCONTINUOUSLY reinforced aluminum {DRA} alloy metal-matrix composites (MMCs) based on particulate, whisker, or short-fiber reinforcements in a 2XXX, 6XXX, or 7XXX series aluminum alloy matrix are attractive and potentially viable materials for weight-sensitive and stiffness-critical components in the burgeoning industries of aerospace, air, and ground transportation and certain consumer-related products.[1–10] These composites have emerged to engender considerable scientific and technological interest because they have a plethora of advantages to offer. Most noteworthy is a 15 to 40 pct increase in strength and a 30 to 100 pct increase in stiffness, compared to the unreinforced alloy,[9–13] while generally maintaining receptiveness to processing and characterization techniques used for the conventional unreinforced (monolithic) counterpart. From an engineering design perspective, the attractiveness in choosing DRA MMCs over contending monolithic counterparts stems from an improvement in specific modulus (E/r), i.e., density-compensated increase in elastic modulus. The moduli obtained are greater than those of typical titanium alloys and only marginally less than those of most steels.[10,12] Associated with an improvement in modulus are concurrent increase in yield strength (sYS) and ultimate tensile strength (sUTS) of up to 60 pct.[9,11,14,15] Furthermore, the DRA MMCs based entirely on particulate reinforcements are attractive and economically affordable material systems, because they can be made with properties that are near isotropic in three orthogonal directions, or in a plane.[3,9,11] Also, conventional metal fabrication methods can be safely used to produce a wide range of product forms, making these materials relatively inexpensive compared to T.S. SRIVATSAN, Professor, is with the Department of Mechanical Engineering, The University of Akron, Akron, OH 44325-3903. R. ANNIGERI, Graduate Student, is with the Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA 16802. This article is based on a presentation made in the Symposium “Mechanisms and Mechanics of Composites Fracture” held October 11–15, 1998, at the TMS Fall Meeting in Rosemont, Illinois, under the auspices of the TMS-SMD/ASM-MSCTS Composite Materials Committee. METALLURGICAL AND MATERIALS TRANSACTIONS A

composites resulting from reinforcing metal matrices with continuous fibers or filaments. The whisker-reinforced composites offer the potential for enhanced properties but suffer from limitations arising as a direct result of whisker damage and breakage during secondary fabrication.[16,17] Incorporation of discontinuous particulate reinforcements in aluminum alloy metal matrices has been shown in some cases to provide noteworthy attributes. A few of these include high abrasion resistance,[18] increased elevated temperature strength,[19] improved creep-rupture properties,[20] good microcreep performance,[21] improved corrosion resistance,[22] and enhanced resistance to the initiation

Data Loading...