Plasticity of a TiCu-based bulk metallic glass: Effect of cooling rate
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Compressive deformation was experimentally investigated for Ti41.5Cu42.5Zr2.5Hf5Ni7.5Si1 bulk metallic glass (BMG) fabricated at different cooling rates. It was found that the ductility of the BMG alloy increased with increasing of the cooling rate in solidification. The alloy with a monolithic amorphous structure exhibited a large ductility, up to 12%. The effect of cooling rate on the ductility of the BMG alloy is interpreted in terms of the variation in amorphous nature and free volume of the as-cast materials.
I. INTRODUCTION
As a class of advanced materials, bulk metallic glasses (BMGs) have gained considerable attention due to their unique properties, including high strength, corrosion resistance, wear resistance, and relatively low elastic modulus, etc., which are rarely found in crystalline materials.1–3 The processing and widespread applications of BMGs are severely inhibited, however, by usually failing catastrophically on one dominant shear band and resulting in very limited macroscopic plastic strain (usually 99.9% in a titanium-gettered high-purity argon atmosphere. The alloy ingots of the desired composition were remelted at © 2007 Materials Research Society IP address: 128.172.10.194
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J. Shen et al.: Plasticity of a TiCu-based bulk metallic glass: Effect of cooling rate
least three times to obtain a high chemical homogeneity. Rodlike amorphous samples were prepared by drop casting the melts into a copper mold, and the obtained samples have a steplike outward appearance, as illustrated in Fig. 1. The microstructure of the as-cast samples was characterized by transmission electron microscopy (TEM). TEM specimens were mechanically thinned and polished to be
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