Mg-Zn-Ca metallic glass

Mg-Zn-Ca metallic glass is a type of amorphous metal.

History

First produced by vapour deposition techniques, thin films of metallically bonded amorphous solids were initially characterised by X-ray diffraction. Despite the significant ramifications to longstanding solidification theory, it was not until 1960 that the first production of amorphous metal from the melt was demonstrated, with splat quenching of near-eutectic Au75Si25at.% producing fully vitreous samples of 10 µm thickness.

Mg-Zn-Ca based metallic glasses are a relatively new group of amorphous metals, possessing commercial and technical advantages over early compositions. Gu and co-workers produced the first Mg-Zn-Ca BMG in 2005, reporting high glass forming ability, high strength and most importantly exceptional plasticity. This lanthanide-free, Mg-based glass attracted immediate interest due to its low density and cost, and particularly because of its uncharacteristically high ductility. This property was unexpected for such compositions, as the constituent elements are found to be of relatively low Poisson ratio, and hence contribute little to the inherent plasticity of the glass. This unlikely asset was seized upon by Li in 2008 who, making use of the Poisson ratio principle, increased Mg content at the expense of Zn to further enhance plasticity. Further improvements were achieved by incremental addition of Ca to the Mg72Zn28 binary composition, producing numerous ternary alloys along the 350oC isotherm of the Mg-Zn-Ca system.

Sources

• BUCKEL, W. & HILSCH, R. (1954) Influence of the condensation at low temperatures on the electrical resistance and the superconductor for different metals. Z. Phys., 138, 109-120.
• KLEMENT, W., WILLENS, R. H. & DUWEZ, P. O. L. (1960) Non-crystalline Structure in Solidified Gold-Silicon Alloys. Nature, 187, 869-870.
• GU, X., SHIFLET, G. J., GUO, F. Q. & POON, S. J. (2005) Mg-Ca-Zn bulk metallic glasses with high strength and significant ductility. Journal of Materials Research, 20, 1935-1938.
• LI, Q.-F., WENG, H.-R., SUO, Z.-Y., REN, Y.-L., YUAN, X.-G. & QIU, K.-Q. (2008) Microstructure and mechanical properties of bulk Mg-Zn-Ca amorphous alloys and amorphous matrix composites. Materials Science and Engineering: A, 487, 301-308.

See also

• Materials science