Titanium-Based Metallic Glass Composites with Good Plasticity

Abstract

Three types of Ti-based alloys (an amorphous material, an amorphous composite with intermetallic crystals, and an intermetallic compound) of the compositions Ti 41.5 Zr 2.5 Hf 5 Cu 42.5-x Ni 7.5+x Si 1 (x = 0, 5, and 15) were fabricated to study the effect of composition on glass formability and microstructure, and the dependence of mechanical properties on microstructure were investigated at room temperature. The results show that the amorphous composite has an excellent combination of both ultrahigh strength (2245 MPa) and large plastic strain (9 pct), which is a significant improvement compared to both the fully amorphous and intermetallic structures. In addition, it is also found that the crystal phases in the amorphous matrix can obstruct the shearing-off of the shear bands by inducing them to interact, deflect, and branch, resulting good plasticity in the amorphous composite.

Thermal stability and crystallization phenomena of low cost Ti-based bulk metallic glass

“…This alloy demonstrated a compressive fracture strength of 1760 MPa, and elastic strain of 2.3% with no significant plasticity. These values are in good agreement with other reported monolithic Ti-based BMGs [1,5].…”

“…Two hour heat treatment to nucleate the phase corresponding to the first exothermic peak yields an XRD spectrum that suggests significant retention of amorphous structure, however, small peaks superimposed on the broad hump are attributed to the primary crystallization (T x1 ) of Ti(Ni,Cu). This result has been reported in previous studies of Ti-based metallic glasses [5]. The secondary crystallization (T x2 ) yielded an XRD spectrum exhibiting sharper, higher intensity peaks, typical of a fully crystalline structure.…”

“…The low cost (relative to other amorphous alloys) of Fe-and Ti-based BMGs, makes them superlative candidates for more widespread commercial application beyond a few niche markets. Titanium glasses in particular present a unique opportunity for commercial application due to their high strength (~2 GPa), elastic strain limit (~2%), low elastic modulus (60-100 GPa), low specific density (~6 g/cm 3 ) and good wear and corrosion resistance [5,6].…”

“…More recently, Ti-based glass forming compositions have been adjusted to promote the nucleation of a ductile crystalline phase within an amorphous matrix. This development has yielded plastic strains as high as 10% in a Ti-Zr-Hf-CuNi-Si BMG composite [5]. A new Ti-based BMG exhibiting excellent thermal stability and designed to exclude Be, rare earth (RE), and other expensive alloying elements is introduced here.…”