Inhomogeneity and glass-forming ability in the bulk metallic glass ${\text{Pd}}_{42.5}{\text{Ni}}_{7.5}{\text{Cu}}_{30}{\text{P}}_{20}$ as seen via x-ray spectroscopies

Core-level photoemission spectroscopy and anomalous x-ray scattering (AXS) measurements were performed for the ${\text{Pd}}_{42.5}{\text{Ni}}_{7.5}{\text{Cu}}_{30}{\text{P}}_{20}$ (PNCP) excellent metallic glass to investigate the chemical nature and local atomic structure, and the results were compared to those in ${\text{Pd}}_{40}{\text{Ni}}_{40}{\text{P}}_{20}$ and ${\text{Pd}}_{40}{\text{Cu}}_{40}{\text{P}}_{20}$. The $\text{P}2p$ core levels clearly separate into two states, indicating that the P atoms have two different chemical sites, which is a strong experimental proof for the existence of an elastic inhomogeneity. From the AXS close to the $\text{Pd}K$ edge, a specific Pd-P-Pd atomic configuration was observed, which is related to the stable state in the $\text{P}2p$ core levels. All of the core levels measured in PNCP have the deepest binding energies among these glasses, indicating the most stable electronic states. Local structure around the P atoms is discussed by the AXS data and a metastable crystal appeared in a supercooled metallic alloy close to PNCP.

Figure 1

(Color online) The PES spectra of (a) $\text{Pd}3d_{5/2}$, (b) $\text{Ni}3p$, and (c) $\text{Cu}3p$ core levels for the PNCP, PNP, and PCP.

Figure 2

(Color online) The PES spectra and the fits of the $\text{P}2p$ core levels for the PNCP, PNP, and PCP. Thin solid and dashed curves denote two components obtained from the fits.

Figure 3

(Color online) The ${\Delta }_{\text{Pd}}S\left(Q\right)$ (circles) and total $S\left(Q\right)$ (solid curves) spectra of PNCP and PNP, and PCP.

Figure 4

(Color online) The DRDF spectra close to the $\text{Pd}K$ edge around the first peak for the PNCP, PNP, and PCP.

Figure 5

(Color online) The binding energies of the core levels reduced to the PNCP values.