Experimental studies of atomic structure, electronic structure, and the electronic transport mechanism in amorphous Al-Cu-Y and Mg-Cu-Y ternary alloys

Abstract

The local atomic structure in the amorphous Al x ͑Cu 0.4 Y 0.6 ͒ 100Ϫx and Mg x ͑Cu 0.4 Y 0.6 ͒ 100Ϫx ͑0рxр85͒ alloys was determined by neutron-diffraction experiments. The electronic structure near the Fermi level was determined using the same samples by means of x-ray photoemission spectroscopy and soft x-ray spectroscopy. Both sets of data are combined to determine self-consistently and uniquely the local atomic structure in both Al-and Mg-based amorphous alloys. The bonding nature and resulting atomic environment are found to depend significantly on whether the third element is Al or Mg. Based on the atomic and electronic structures thus derived, we could interpret the Al or Mg concentration dependence of the crystallization temperature, electronic specific-heat coefficient, and also that of the resistivity value of 300 K. The origin of the appearance of a positive Hall coefficient observed in the Al-based amorphous alloys but not in the Mg-based amorphous alloys is also briefly discussed.

Evaluation of glass-forming ability in metals using multi-model techniques

“…In this case, the CSRO modeling suggests that the atomic structure will be tending towards a solvent-solute type topology, as Y (solvent) has a negative CSRO with both solutes. This tendency matches that seen in the experimental results as the solute-solute clustering has disappeared, and Y clustering around solute atoms, especially Cu, has begun to develop, as seen in the Mg 30 Cu 26 Y 42 illustration [14].…”

“…The reported radial distribution function [14] of amorphous Mg 80 Cu 8 Y 12 indicated primarily Mg-Mg and Cu-Y correlations. It was concluded experimentally that in the Mg 80 Cu 6 Y 12 alloy, the amorphous structure consisted of Cu-Y clusters surrounded by a randomly distributed Mg matrix, as the CSRO predicts.…”

“…2a, where the illustrations are direct reproductions from the published work [14]. In this plot the CSRO between each binary element pair is compared to the atomic structure derived from the experiment [14], where the vertical lines are drawn connecting the illustrations to the composition that they represent. At 80% Mg, the CSRO is dominated by Cu-Y attraction, as indicated by a CSRO of −0.9.…”

Predicting Composition Dependence of Glass Forming Ability in Ternary Al-Cu-Y System by Thermodynamic Calculation

“…For example, Inoue et al have prepared a series of Al-Cu-Y metallic glasses within the composition range of 3-22 at% Y by melt spinning and found that when the Al content is more than 80 at%, the metallic glasses have good bend ductility [20,21]. Fukunaga et al, have obtained Alx(Cu0.4Y0.6)100−x (x = 0, 5, 10, 15, 20, 30, 80, and 85) metallic glasses by arc melting and further studied their atomic and electronic structures [31]. In addition, Idzikowski et al have obtained fully amorphous Al8Cu42Y50 ribbon by melt-spinning and further tracked its structural evolution with varying annealing time [32].…”

“…To further validate the predicted GFR of the Al-Cu-Y system, the experimental identified glass formation compositions reported so far in the literature are extensively collected [20,21,[30][31][32][33] and marked by the red dots in Figure 1. For example, Inoue et al have prepared a series of Al-Cu-Y metallic glasses within the composition range of 3-22 at% Y by melt spinning and found that when the Al content is more than 80 at%, the metallic glasses have good bend ductility [20,21].…”