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Metal Alloy Essay

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Latest, novel engineering metal alloys have attracted considerable attention from research groups and industrial facilities globally because of their remarkable properties. Metallic glasses, or amorphous metals, are metallic alloys with non-crystalline structures. Instead, it has a disordered structure, with atoms occupying random positions in a lack of long-range order, as can be schematically seen in Figure 2.1. Figure 2.1 - Atomic structure of Cu65Zr35 glass, Cu atoms: red, Zr atoms: blue. Source: Mattern et al. (2009). This material class was first disclosed in the 60's. An Au75Si25 metallic glass alloy was synthesized from the melt at Caltech (KLEMENT; WILLENS and DUWEZ, 1960). This and other first glass-forming alloys had to…show more content…
2.1), of the glass transition temperature (Tg) to the melting point (Tm), or liquidus temperature (Tl) of an alloy, could be used as a criterion for determining the glass-forming ability of an alloy (WANG, DONG and SHEK, 2004, p. 45). T_rg=T_g/T_m (Eq. 2.1) In the late 80s, the greater stabilization of the supercooled liquid started the production of the so-called bulk metallic glasses (BMGs). With thicknesses that could reach 10 mm or more, with various alloys formed from early transition metals (Zr, Ti and Hf) and production of alloys containing late transition metals (Fe-Al-Ga-P-B), due to the low production cost (MILLER and LIAW, 2007). Present-day, BMGs of the systems based on Zr, Zr–Be, Pd, Pt, Mg, La, Ni, and Cu can be formed with diameters >2 cm, and Fe, Co and Ti based BMG can be produced with diameters >1 cm, fabricated by the cooper mold casting techniques (INOUE and TAKEUCHI, 2011). Figure 2.2 presents a few of the bulk amorphous alloys developed to date. BMGs can be formed by means of vast production methods: water-quenching, copper-mold casting, high-pressure die casting, arc melting, unidirectional melting, suction casting, and squeeze casting (MILLER; LIAW, 2007). Electromechanical conformation (OLIVEIRA et al., 2002), and warm extrusion of atomized amorphous powders in the supercooled liquid region are used techniques (INOUE, 2000). Figure 2.2 - Pd-, Ni-,
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