Nanocrystal evolution in bulk amorphous Zr57Cu20Al10Ni8Ti5 alloy and its mechanical properties

Effects of Ta on Microstructure and Mechanical Property of Ti-Zr-Cu-Pd-Ta Alloys

“…Partially crystallized glassy alloy up to 45% crystallization exhibited higher strength in Zr-Ti-Ni-Cu- Al bulk metallic glasses. 7) The amount of plastic deformation for the Zr-Ti-Ni-Cu-Al alloy decreased when the crystalline fraction was higher than 40%. In this case, a further increase of Ta content up to 3% and 5%, decreases the glass-forming ability, resulting in the crystallization fraction of 50% and 65%.…”

“…Accordingly a number of porosities can be observed all over the fracture surface. Xing et al 7) found that the crystalline fraction of 40%-45% leaded to the change in the fracture surface from ductile to brittle type and porosity played an important role in multiple cracking of annealed alloys. 20) On the side surface, a few straight and separated shear bands are observed near the fracture in the base alloy (Fig.…”

“…13) On the other hand, although the dispersion of nanoparticles or dendrites is often beneficial to the improvement of ductility, an appropriate volume fraction of the enforcing phases is still very important in simultaneous achievement of good ductility and high strength. 7) As mentioned in experimental procedure, the sample dimensions are same, i.e., for each composition the cooling rate is same, so for the lower glass-forming alloy and higher Ta-containing alloy the cooling rate is not high enough to form a single glassy state. There is high volume fraction over 50% of quench-in Ti 3 Cu 4 crystalline phases in the 3% Ta-containing alloy.…”

“…1,2) The ex-situ technique is charactered by the introduction of extraneous fibres or particles into bulk metallic glasses before casting process. 1,3) In-situ formed composites can be synthesized trough annealing of metallic glass precursors, [4][5][6][7] and slightly adjusting composition 2,8) or cooling rate of the cast glasses 9,10) to produce a metallic glass matrix with dispersed crystalline phases. The bulk metallic glass composites show significantly improved plastic deformation comparing with the monolithic glass.…”

Formation and Mechanical Properties of Ti-Zr-Ni-Cu Amorphous Alloy Containing Icosahedral Nanoscale Quasicrystalline Phase

“…The high strength nanocrystalline and amorphous materials have been reported. 12,13) The reasons for the high strength can be concluded as: (1) the residual amorphous phase can contain a large amount of free volume and high thermal stability resulting from the enrichment in the solute element, (2) the amorphous/nanocrystal interface has a high degree of packing fraction due to the low interface energy at the liquid/solid interface, (3) the nanocrystal with a uniform particle size disperses homogeneously and isolately in coexistence with the amorphous intergranular phase. As shown in Table 1, the homogeneous dispersion and nano size of the I-phase particles are considered to be the dominant factors for improving the mechanical strength of the melt-spun TiZrNiCu alloy.…”