Abstract
The amorphous Cu46Zr42Al7Y5 alloy presents large supercooled liquid region (ΔTX = 100 K), with a viscosity of about 106 N.s/m2 where the material can flow as a liquid, making it possible an easy deformation in this temperature region. The aim of this work was to analyze processing routes to produce bulks of metallic glasses. Two kinds of materials were used: amorphous powders and ribbons, both were consolidated by hot extrusion in temperatures inside the range between Tg and Tx, with a ram speed of 1 mm/min and extrusion ratio of 3 : 1. Analysis of X-Ray Diffratometry (XRD), Differential Scanning Calorimetry (DSC) and Scanning Electron Microscopy (SEM), revealed that the proposed consolidation routes were effective to produce large bulks of amorphous materials, even with the strong decreasing of ΔTX observed after deformation by milling and during extrusion.
Highlights
Bulk metallic glasses (BMG) of copper based alloys show a scientific and engineering importance due to its higher strength and ductility1-3
The exothermic peak seen before the glass transition is the result of annihilation of excess free volume
The free volume was decreased after the ribbon extrusion
Summary
Bulk metallic glasses (BMG) of copper based alloys show a scientific and engineering importance due to its higher strength and ductility. The presence of aluminum, in the ternary Cu50Zr45Al5alloy, increases the GFA and the critical casting thickness can be increased up to 3 mm This alloy shows a large supercooled liquid region (∆Tx = Tx – Tg), ∆Tx = 72 K, and a high reduced glass transition temperature (Trg = Tg/Tl), Trg = 0,61[8]. Large ∆Tx is an important feature because when metallic glasses are deformed inside this temperature region they exhibit homogeneous deformation with significant plasticity without crystallization. Considering these aspects, large BMGs can be produced by consolidation from amorphous powders or directly from amorphous ribbons. In this article, such kinds of materials were consolidated by extrusion; in temperatures inside the supercooled liquid region to compare their microstructural characteristics and thermal behaviors
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