Nano-Mechanical Study of Mechanically Alloyed Zr-Cu-Al-Ni Glass Composite Containing Second-Phase ZrC Particles
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Nano-Mechanical Study of Mechanically Alloyed Zr-Cu-Al-Ni Glass Composite Containing Second-Phase ZrC Particles Germán Alcalá1, Sonia Mato1, Stefano Deledda1, Martin Knieps2, Ude Hangen2, Jürgen Eckert3, Annett Gebert1 and Ludwig Schultz1 1
IFW Dresden, Institute for Metallic Materials, P.O. Box 27 00 16, D-01171 Dresden, Germany SURFACE, Rheinstr.7, D-41836 Hückelhoven, Germany 3 TU Darmstadt, Material Science, Physical Metallurgy, Petersenstr. 23, D-64287 Darmstadt, Germany 2
Abstract Metallic glasses exhibit generally high hardness and elastic modulus values at the expense of very limited plasticity. The incorporation of crystalline particles within an amorphous metallic matrix has been widely reported to improve the performance of these materials by reducing crack propagation. The present work analyzes the influence of nanometer-size ZrC particles on the nano-mechanical behavior of mechanically alloyed Zr55Cu30Al10Ni5 glassy matrix composites. The volume fraction of ZrC particles ranged from zero up to 20 vol. %, showing a critical change in the mechanical behavior between 10 and 20 vol. %, particularly in the elastic response. Introduction The production of Zr-based bulk metallic glasses is feasible by standard casting techniques at cooling rate as low as 1K min-1[1,2] as well as by the mechanical alloying of elemental powders[3] followed by hot powder consolidation techniques .This is mainly due to the high glass forming ability of such systems[1-5] and their high stability against crystallization[1,2]. The incorporation of a second crystalline phase in amorphous alloys has been reported to have an effect in the deformation behavior of these materials, increasing their ductility[2,6-8]. There are two possible ways to obtain a second phase within an amorphous alloy. Either partial devitrification is forced upon annealing or hot working over the glass transition temperature[9,10], or mechanical alloying of elemental powders with insoluble particles is carried out to produce metallic glasses with crystalline precipitates by intermixing and mechanically activated interdiffusion[3,11,12]. The present work is focused on the nanomechanical response of the Zr55Cu30Al10Ni5 alloy with different concentrations of ZrC nanocrystals prepared by mechanical alloying. Experimental The samples under investigation were produced by mechanical alloying in a Retsch PM 4000 planetary ball mill. Hardened steel balls, vials, and a ball-to-powder ratio of 14:1 were used in the process. A starting powder mixture consisting on elemental metallic powders (purity ≥ 99.9% ) with nominal composition Zr55Cu30Al10Ni5 was blended with 10, and 20 vol.% of ZrC particles (-325 Mesh, 99.5% purity). Powder handling was carried out in a glove box under a purified argon atmosphere (
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