Deformation and Failure Mechanisms in a Magnesium Alloy Under Uniaxial Compressive Loading
- PDF / 4,437,920 Bytes
- 14 Pages / 595.276 x 790.866 pts Page_size
- 92 Downloads / 237 Views
RESEARCH PAPER
Deformation and Failure Mechanisms in a Magnesium Alloy Under Uniaxial Compressive Loading Meng Zhao1,2 · K. T. Ramesh1,2 Received: 27 June 2019 / Accepted: 1 April 2020 © Society for Experimental Mechanics, Inc 2020
Abstract We have investigated the deformation and failure mechanisms of a rolled AZ31B magnesium alloy under both quasi-static ( 10−3 to 10−2 s−1 ) and dynamic ( 103 s−1 ) compressive loading. The observed anisotropy in the plastic response originates from the different in-plane and out-of-plane deformation mechanisms activated when the loading orientation changes. For plasticity driven by extension twins, extension twin–twin boundaries were found to dominate in the late stage of deformation. Severe localization was observed after deformation mediated by pyramidal slip and contraction twinning compared to the deformation mainly caused by extension twinning. The fracture process was established as a function of both loading rate and loading orientation. Moreover, the intermetallic inclusions in the material, which appeared to be hard and brittle, might lead to macroscopic fracture under compressive loading. Keywords Mechanisms · Twin–twin boundary · Localization · Inclusions
Introduction The compelling need for low-cost, lightweight, energyefficient and environment-friendly structural materials has spurred enormous efforts to search for alternatives to the conventional materials found in transportation, energy and propulsion applications. Magnesium (Mg), as the eighth most abundant element in the earth’s crust, has attracted a lot of attention over the last decade due to its low density, which is 30% less than aluminum and only 25% of steel. Its low density and high specific strength (strength-to-density ratio) provides excellent opportunities for lightweight applications in transportation and consumer electronics [1–4]. With good bio-compatibility in the human body, Mg is also emerging in medical applications, such as in bio-degradable and bio-absorbable implants [5]. Despite these benefits, it is not simple to incorporate Mg alloys into structures as a direct substitution for steel and aluminum alloys. The anisotropy of the material creates many challenges in processing. * Meng Zhao [email protected] 1
Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
Hopkins Extreme Materials Institute, Johns Hopkins University, Baltimore, MD 21218, USA
2
In addition, the limited room-temperature formability prevents easy casting of Mg parts for structural applications. Mg alloys often develop strong textures after processing, resulting in plastic anisotropy. This anisotropy is believed to originate from the complex deformation mechanisms inherent to the material. In Mg, basal ⟨a⟩ slip and prismatic ⟨a⟩ slip, each having two independent modes, permit shear in ̄ ̄ has four 20⟩ the basal plane. Pyramidal ⟨a⟩ slip {1101}⟨11 independent modes and can also allow shear in the basal plane, but these modes are crystallographically equivalent to the combined fo
Data Loading...
