Crystallization from an amorphous atomic structure is usually seen as a spontaneous process in pursuit of a lower energy state, but for alloy systems it is often hard to elucidate because of the intrinsic structural and compositional complexity. Here, by means of electron beam irradiation, we found surface-limited, and thus size-dependent crystallization in a system of monoatomic Pd metallic glass, which is ascribed to the structural differences between the surface and the interior. The equilibrium thickness of the surface crystallization is controllable, presenting a promising approach to fabricate novel nanostructures. The investigation is believed to provide a general understanding of solid amorphous-to-crystalline phase transition from the nanoscale to the bulk size.
Crystallization of metallic glass as a grain-boundary nucleated process: experimental and theoretical evidence for the grain structure of metallic glasses
By combining atomistic simulations with a detailed analysis of individual atomic hops, we show that the diffusion of carbon in a binary Fe-C glass exhibits strong (anti-)correlations and is largely determined by the local environment. Higher local carbon concentrations lead to slower atomic mobility. Our results help explain the increasing stability of Fe-C (and other similar metal-metalloid glasses) against crystallization with increasing carbon concentration.
Primary crystallization in high Al-content metallic glasses is driven by nanometer-diameter regions with internal structure similar to fcc Al. Comparison of fluctuation electron microscopy (FEM) data to FEM simulations of fcc Al clusters dispersed in a dense-random packed matrix is used to extract the diameter and volume fraction of the ordered regions in a Al88Y7Fe5 base glass and in glasses with 1 at.% Cu substituted for Y or Al. The size and density of nanocrystals were measured as a function of isothermal annealing time for the same alloys. The volume fraction of crystalline material grows…
Crystallization kinetics has features that are universal and independent of the type of crystallized system. The possibility of using scaling relations to describe the temperature dependences of the surface self-diffusion coefficient $D_s$, which is one of the key characteristics of crystallization kinetics, has been demonstrated in application to various crystallized molecular glasses. It has been shown that the surface self-diffusion coefficient $D_s$ as a function of the dimensionless temperature is reproduced by a power law and is universally scaled for all considered systems. The analysis…
Microstructure-specific mechanisms define multistage relaxation dynamics in a metallic model-glass
Federal Institute of Materials Research and Testing (BAM)（联邦材料研究和测试研究所）；Technical University of Munich（慕尼黑工业大学）；University of Illinois at Urbana-Champaign（伊利诺伊大学厄巴纳-香槟分校）
Thin film metallic glasses undergoing devitrification can form partially crystallized or fully crystallized materials with novel structural and magnetic properties. The development of desired and tunable properties of such systems drives the need to understand the mechanism of their thermal evolution at the atomic level. Co-sputtered amorphous Ni-Zr alloy thin films which were thermally annealed in steps of 200 deg C from room temperature up to 800 deg C, were observed to undergo an amorphous-to-crystalline transformation. Evolutions in local atomic structure, including oxide formation and dep…
Graph Learning Metallic Glass Discovery from Wikipedia
Songshan Lake Materials Laboratory（松山湖材料实验室）；Department of Physics, University of Science and Technology of China（中国科学技术大学物理系）；Lawrence Berkeley National Laboratory（伯克利国家实验室）；Institute of Physics, Chinese Academy of Sciences（中国科学院物理研究所）
