Development and Characterization of Low-Density Ca-Based Bulk Metallic Glasses: An Overview

Abstract

Ca-based bulk metallic glasses (BMGs) have unique properties and represent a new seventh group of BMGs. Many of them have excellent GFA, which can be related to their efficient atomic packing, low onset driving force for crystallization, and high viscosity (high relaxation time) of the supercooled liquid. The Ca-based glasses have the lowest density and elastic moduli among all BMGs discovered to date. Unfortunately, as many other glasses, Ca-based BMGs are brittle below the glass transition temperature, and they also have marginal oxidation and corrosion resistance. The latter can be improved by proper selection of alloying elements. In this article, we review recent work on the development of low-density Ca-based BMGs and discuss the effect of alloy composition on the thermal, physical, and chemical properties of these glasses.

Review on the Research and Development of Ti-Based Bulk Metallic Glasses

“…Encouraged by this success, with the effort of scholars all over the world, a number of Ti-based BMGs, such as Ti-Cu-Ni [40,41], Ti-Zr-Be [42,43], Ti-Zr-Cu-Ni-Sn [44,45], Ti-Zr-Cu-Pd-(Sn, Si, Nb) [46][47][48][49][50], Ti-Zr-Cu-Ni-Be [51][52][53], Ti-Zr-Hf-Cu-Ni-Si-Sn [54], and Ti-Cu-Zr-Fe-Sn-Si-(Ag, Sc) [55][56][57], have been developed over the last few decades. Figure 1 shows the maximum diameters for glass formation obtained in different alloy systems and the year in which they were discovered [8,[58][59][60][61][62][63][64][65][66][67][68][69][70][71][72][73]. Compared with other alloy systems (e.g., Zr-, Pd-, Mg-, Fe-, Co-, Ni-, and Cu-based So far, the largest known critical diameter for Ti-based BMGs has been over 50 mm in the Ti-Zr-Cu-Ni-Be [72] and Ti-Zr-Cu-Fe-Be [73] quinary alloy systems.…”

“…Maximum diameters of the bulk metallic glass (BMG) rods achieved in different alloy systems and the years in which they were discovered. Data are taken from [8,[58][59][60][61][62][63][64][65][66][67][68][69][70][71][72][73].…”

Compositions of Al-Based Quasicrystals Interpreted by Cluster Formulae

“…Cluster formulae Since it is dicult to assign the e/a contributions from TMs in ternary QCs, here we adopt an alter- M A = C i M i is the average molecular mass of the alloy, C i and M i represent the atomic fraction and atomic mass of the i-th element, ρ is the mass density, which can be estimated by ρ = (C i M i )/ (C i M i /ρ i ) [12], where ρ i is the mass density of a pure element i. With the help of the estimated atomic density ρ a , the radius of the cluster r 1 and the number of atoms in unit cluster formula Z, e/u is then assessable.…”

Ca–Mg–Zn–(Ag) bulk metallic glasses prepared by unidirectional quenching

“…T g decreases from 380K to 376K, T x1 decreases from 423 K to 411 K and T x3 also has the decreasing tendency from 490 K to 483 K, when the concentration of Ca increases from 60% to 70% and the concentrations of Mg and Zn decrease. The feature that characteristic temperatures vary with the concentrations of constituent elements also can be seen in other CaeMgeZn compositions [13].…”