Abstract
Consolidation of amorphous powders, which take advantage of the supercooled liquid region, is an alternative way to overcome the size limitation in marginal metallic glasses. Cu36Ti34Zr22Ni8based amorphous powders were obtained during high energy ball-milling. The analyses revealed that amorphous structures of powders and ribbons are quite different and this led to a different thermal behavior being the powders more thermally stable than the ribbons. Extrusion was initially proposed as a consolidation process; however, the decrease in viscosity in remainder amorphous matrix was not sufficient for that process, but certainly sufficient for sintering the sample during hot consolidation. An amorphous/nanocrystalline microstructure known for enhancing the mechanical properties of their fully amorphous counterparts was obtained. Evaluation of mechanical properties by microhardness revealed the relatively high hardness of HV 768. From these results, consolidation by sintering seems a promising route to produce bulk metallic glasses nanocomposites.
Highlights
Cu-Ti based bulk metallic glasses (BMG) alloys have attracted interest due to their superior mechanical properties and relatively lower costs[1,2,3,4]
Consolidation of amorphous powder can be achieved by ultra-high pressure (UHP), by taking advantage of the decrease in viscosity of the supercooled-liquid region[10], sintering-spark plasma (SPS)[11,12,13], equal channel angular extrusion (ECAE)[14] and extrusion[15]
In comparison with amorphous alloys obtained by rapid solidification, the amorphization through reactions in the solid state has, in principle, the advantage to lead to techniques for producing bulky amorphous materials[21]
Summary
Cu-Ti based bulk metallic glasses (BMG) alloys have attracted interest due to their superior mechanical properties and relatively lower costs[1,2,3,4]. The lack of ductility has limited the applications To overcome this problem, composites of embedded nanocrystals in the Cu-Ti glassy matrix are being developed.[5, 6]. The route of solid state amorphization followed by powder consolidation appears to be an attractive route to produce sized BMGs in alloy systems with marginal glass forming ability, as is the case of Cu‐Ti‐based alloys. According to preliminary tests[16 ], the Cu36Ti34Zr22Ni8 alloy is a strong candidate to form metallic glass. It has been shown[16] that this alloy presents amorphous phase formation when processed by melt spinning showing supercooled-liquid region (ΔTx=Tx–Tg), ΔTX = 67K16. The Assuming that Cu and Ni are similar, Cu36Ti34Zr22Ni8 composition is located near to deep eutectic in a Cu-Ti-Zr ternary phase diagram, which decreases the
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