Nanocrystalline composites with high strength obtained in Zr–Ti–Ni–Cu–Al bulk amorphous alloys

The Zr-Cu-Al bulk amorphous (BA) alloys, which have no long-range ordered structure, possess various properties such as high strength and toughness with compositional dependence. In the present study, in order to estimate the natures of local structure change and relaxation behavior of hyper-eutectic BA alloys during annealing, positron annihilation measurements and density measurement have been performed for hyper-eutectic Zr-Cu-Al BA alloys with annealing. The enthalpy relaxation and structural relaxation was also measured by differential scanning calorimetry (DSC) measurement. These results show that the relaxation process of free volume containing in hyper-eutectic BA alloys is different from that in hypo-eutectic alloys.

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Mg–Ca–Zn Bulk Metallic Glasses with High Strength and Significant Ductility

Journal of Materials Research ◽

10.1557/jmr.2005.0245 ◽

2005 ◽

Vol 20 (8) ◽

pp. 1935-1938 ◽

Cited By ~ 110

Author(s):

X. Gu ◽

G.J. Shiflet ◽

F.Q. Guo ◽

S.J. Poon

Keyword(s):

Metallic Glasses ◽

Amorphous Alloys ◽

Mass Density ◽

High Strength ◽

Light Metal ◽

Glass Forming Ability ◽

Bulk Glass ◽

Bulk Amorphous Alloys ◽

Specific Strength ◽

Glass Forming

The development of Mg–Ca–Zn metallic glasses with improved bulk glass forming ability, high strength, and significant ductility is reported. A typical size of at least 3–4 mm amorphous samples can be prepared using conventional casting techniques. By varying the composition, the mass density of these light metal based bulk amorphous alloys ranges from 2.0 to 3.0 g/cm3. The typical measured microhardness is 2.16 GPa, corresponding to a fracture strength of about 700 MPa and specific strength of around 250–300 MPa cm3/g. Unlike other Mg- or Ca-based metallic glasses, the present Mg–Ca–Zn amorphous alloys show significant ductility.

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Bulk Glass Formation in an Fe-Based Fe–Y–Zr–M (M = Cr, Co, Al)–Mo–B System

Journal of Materials Research ◽

10.1557/jmr.2004.19.3.921 ◽

2004 ◽

Vol 19 (3) ◽

pp. 921-929 ◽

Cited By ~ 35

Author(s):

Z.P. Lu ◽

C.T. Liu ◽

C.A. Carmichael ◽

W.D. Porter ◽

S.C. Deevi

Keyword(s):

Metallic Glasses ◽

Glass Formation ◽

Amorphous Alloys ◽

High Strength ◽

Supercooled Liquid ◽

Glass Forming Ability ◽

Bulk Glass ◽

Bulk Amorphous Alloys ◽

Glass Forming ◽

Hardness Values

Several new bulk metallic glasses based on Fe–Y–Zr–(Co, Cr, Al)–Mo–B, which have a glass-forming ability superior to the best composition Fe61Zr10Co7Mo5W2B15 reported recently, have been successfully developed. The as-cast bulk amorphous alloys showed a distinctly high thermal stability with glass-transition temperatures above 900 K, supercooled liquid regions above 60 K, and high strength with Vickers hardness values larger than HV 1200. The suppression of the growth of primary phases in the molten liquids and the resultant low liquidus temperatures were found to be responsible for the superior glass-forming ability in these new alloys. It was found that the addition of 2% Y not only facilitated bulk glass formation, but the neutralizing effect of Y with oxygen in the molten liquids also improved the manufacturability of these amorphous alloys.

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