Abstract
Elastic deformation behaviors of as-cast and annealed eutectic and hypoeutectic Zr–Cu–Al bulk metallic glasses (BMG) were investigated on a basis of different strain-scales, determined by X-ray scattering and the strain gauge. The microscopic strains determined by Direct-space method and Reciprocal-space method were compared with the macroscopic strain measured by the strain gauge, and the difference in the deformation mechanism between eutectic and hypoeutectic Zr–Cu–Al BMGs was investigated by their correlation. The eutectic Zr50Cu40Al10 BMG obtains more homogeneous microstructure by free-volume annihilation after annealing, improving a resistance to deformation but degrading ductility because of a decrease in the volume fraction of weakly-bonded regions with relatively high mobility. On the other hand, the as-cast hypoeutectic Zr60Cu30Al10 BMG originally has homogeneous microstructure but loses its structural and elastic homogeneities because of nanocluster formation after annealing. Such structural changes by annealing might develop unique mechanical properties showing no degradations of ductility and toughness for the structural-relaxed hypoeutectic Zr60Cu30Al10 BMGs.
Highlights
Bulk metallic glasses (BMG) exhibit interesting mechanical features such as high strength with high ductility, which is a different trend from typical metallic materials
The fatigue property on the hypoeutectic bulk metallic glasses (BMG) is independent of the annealing temperature, while that on a eutectic BMG changes after annealing
Crystal-like ordering and icosahedral-like contrast are partially recognized in the amorphous glassy matrix after annealing in the hypoeutectic BMG, while the annealed eutectic BMG has homogeneous amorphous, glassy structure
Summary
Bulk metallic glasses (BMG) exhibit interesting mechanical features such as high strength with high ductility (low Young’s modulus), which is a different trend from typical metallic materials. Recently found that a hypoeutectic Zr–Cu–Al BMG with a Zr composition of 10% more than the Metals 2016, 6, 12; doi:10.3390/met6010012 www.mdpi.com/journal/metals. Metals 2016, 6, 12 eutectic composition shows no degradations of ductility and toughness after complete structural relaxation [1,2]. The fatigue property on the hypoeutectic BMG is independent of the annealing temperature, while that on a eutectic BMG changes after annealing. Crystal-like ordering and icosahedral-like contrast are partially recognized in the amorphous glassy matrix after annealing in the hypoeutectic BMG, while the annealed eutectic BMG has homogeneous amorphous, glassy structure. The microstructural changes after structural relaxation might be a crucial factor to affect the mechanical and physical properties of BMGs after annealing
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
