The polyamorphsim in amorphous materials is one of the most fascinating topics in condensed matter physics. In amorphous metals, the nature of polyamorphic transformation is poorly understood. Here we investigate the structural evolution of a Ce-based metallic glass (MG) with pressure at room temperature (RT) and near the glass transition temperature by synchrotron X-ray diffraction, uncovering novel behaviours. The MG shows hierarchical densification processes at both temperatures, arising from the hierarchy of interatomic interactions. In contrast with a continuous and smooth process for the low-to medium-density amorphous state transformation at RT, a relatively abrupt and discontinuous transformation around 5.5 GPa is observed at 390 K, suggesting a possible weak first-order nature. Furthermore, both positive and abnormal-negative thermal expansion behaviours on medium-range order are observed in different pressure windows, which could be related to the low-energy vibrational motions and relaxation of the weakly linked solute-centred clusters.

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amorphous coatings have been prepared by the activated combustion high velocity air fuel (AC-HVAF) and high velocity oxygen fuel (HVOF) processes. The microstructure and wear resistance of the amorphous coatings are comparatively studied. The wear volume loss of the AC-HVAF coating is approximately seven times less than that of the HVOF coating, indicating that the AC-HVAF coating exhibits better wear resistance. Detailed analysis on the worn surface indicates that the enhanced wear resistance of the AC-HVAF coating is mainly attributed to the formation of a more stable oxide tribolayer and smoother worn surface, which result from the dense and complete amorphous microstructure of the AC-HVAF coating. The wear mechanism of the amorphous coatings is dominated by oxidation wear.

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The electrochemical corrosion and passive behavior of activated combustion high-velocity air fuel FeCrMoMnWBCSi amorphous metallic coatings (AMCs) under different geometries that produced a variable tensile residual stresses were investigated in chloride-containing solutions by using electrochemical measurements and X-ray photoelectron spectroscopy. The tensile residual stresses of AMCs were determined by the mechanical method of sharp indentation testing. A systematic detrimental effect of tensile residual stress on passive current density and localized corrosion was found. The detrimental effect of residual stress was aggravated at higher temperatures and acidity. The implication of high donor density on the passive film stability, derived from Mott-Schottky analysis, is also discussed.