In Situ Scattering Studies of Crystallization Kinetics in a Phase-Separated Zr–Cu–Fe–Al Bulk Metallic Glass

Abstract

Thermal stability and the crystallization kinetics of a phase-separated Zr-Cu-Fe-Al bulk metallic glass were investigated using in situ high-energy synchrotron X-ray and neutron diffraction, as well as small-angle synchrotron X-ray scattering. It was revealed that this glass with excellent glass-forming ability possesses a two-step crystallization behavior. The crystalline products and their evolution sequence are more complicated than a homogeneous Zr-Cu-Al glass with average glass-forming ability. The experimental results indicate that a finely distributed nanometer-sized cubic Zr 2 Cu phase forms first and then transforms to a tetragonal Zr 2 Cu phase, while the matrix transforms to an orthorhombic Zr 3 Fe phase. The strength of the Zr-Cu-Fe-Al composite containing cubic Zr 2 Cu phase and glass matrix increases, and the plasticity also improves compared to the as-cast Zr-Cu-Fe-Al bulk metallic glass. Our results suggest that the formation of multiple and complex crystalline products would be the characteristics of the Zr-Cu-Fe-Al glass with better glass-forming ability. Our study may shed light on the synthesis of bulk-sized glass-nanocrystals composites of high strength and good plasticity.

Mechanical properties and thermal stability of ZrCuAlx thin film metallic glasses: Experiments and first-principle calculations

“…Cubic CuZr 2 , tetragonal CuZr 2 and cubic ZrCu phases are formed during the crystallization. The formation of tetragonal CuZr 2 has been observed in other works in annealed ZrCu [11,54] and in particular Liu et al showed by synchrotron diffraction that during annealing tetragonal CuZr 2 transforms into cubic CuZr 2 in ZrCuAl alloys [55].…”

Engineering Atomic-to-Nano Scale Structural Homogeneity towards High Corrosion Resistance of Amorphous Magnesium-Based Alloys

“…The first S(Q) peak shows a lower peak position and a narrower peak width after T C treatment, which indicates that the local order is extended to the medium range and the atomic packing is less dense than the matrix. The structural correlation is enhanced from the short to the medium range (~5-10 Å) during this process, due to the recombination of the local atomic units [22,46,47]. To summarize, the nanoscale thermodynamically-favored metastable amorphous heterogeneous region with an average diameter of 5.4 nm is uniformly distributed in the amorphous alloy matrix.…”

“…The first S(Q) peak shows a lower peak position and a narrower peak width after TC treatment, which indicates that the local order is extended to the medium range and the atomic packing is less dense than the matrix. The structural correlation is enhanced from the short to the medium range (~5-10 Å) during this process, due to the recombination of the local atomic units [22,46,47]. To summarize, the nanoscale thermodynamically-favored metastable amorphous heterogeneous region with an Down to the nanoscale, an interference peak occurs in the T C -treated sample whereas it does not exist in the as-cast sample according to the results of SAXS (Figure 1c), which suggests the occurrence of nanoscale heterogeneity different from the amorphous matrix in the T C -treated sample [28,[38][39][40].…”

“…When heating amorphous alloys before melting, typically, several phase transition processes occur in sequence, including separation into amorphous phases with different components [18,19], liquid-liquid phase transition [20,21], and crystallization [22,23]. Among these processes, the liquid-liquid phase transition involves only rearrangement of local structural units and no component variation in the amorphous alloys without a long-range order [24,25].…”