Tohoku University · Engineering
Professor A.L. Greer's research lab focuses on the fundamental science and engineering of metallic glasses and amorphous alloys, with a strong emphasis on microstructural design, nucleation control in solidification, and the mechanical behavior of non-crystalline materials. Key research directions include the mechanisms of inoculation in aluminum alloys, the rejuvenation of metallic glasses to enhance plasticity, and the role of microstructure in wear resistance and mechanical performance. The lab combines advanced characterization techniques—such as transmission electron microscopy and in-situ mechanical testing—with theoretical modeling to understand and tailor material properties at the atomic and microscale levels.
Figures are computed from collected data and may differ slightly.
Metallic glasses, first discovered nearly 50 years ago, are currently among the most actively studied metallic materials. Available in sections up to several centimeters, with many novel, applicable properties, metallic glasses have also been the focus of research advancing our understanding of liquids and of glasses in general. Here we outline some key features of the glassy state in metals. The next few years will bring exciting advances, as we are on the threshold of exploiting new opportunit
AbstractAbstractAmorphous alloys, and the partially or fully crystallised materials derived from them, can have properties attractive for a diverse range of applications. In some cases, their wear resistance can be of primary concern, in others, it is an important secondary property. The distinctive mechanical properties of amorphous alloys make their wear resistance of fundamental interest also. This review focuses on the influence of a variety of factors in wear testing, on the mechanisms of w
Abstract A review is given of the studies of aluminium inoculation undertaken within the EU Network “Microstructural Engineering by Solidification Processing” (MEBSP). A wide range of studies of industrial practice of grain refining and of the fundamental mechanisms of nucleation and growth have contributed to improved understanding. Particular advances have been made in understanding the relative performance of different grain refiners.
Rejuvenation of metallic glasses, bringing them to higher-energy states, is of interest in improving their plasticity. The mechanisms of rejuvenation are poorly understood, and its limits remain unexplored. We use constrained loading in compression to impose substantial plastic flow on a zirconium-based bulk metallic glass. The maximum measured effects are that the hardness of the glass decreases by 36%, and its excess enthalpy (above the relaxed state) increases to 41% of the enthalpy of meltin
In all of metallurgical processing, probably the most prominent example of nucleation control is the "inoculation" of melts to suppress columnar solidification and to obtain fine equiaxed grain structures in the as-cast solid. In inoculation, a master alloy is added to the melt to increase its solute content and to add stable particles that can act as nucleants for solid grains. This is important for alloys of many metals, and in other cases such as ice nucleation in living systems, but inoculat
Recent progress in understanding the inoculation of aluminium melts is reviewed. Transmission electron microscopy of inoculant particles in a metallic glass reveals details of the mechanism of nucleation of aluminium grains. While such studies define some of the conditions under which inoculation is effective or not, they do not permit a prediction of grain size. Unusually for a nucleation–related phenomenon, quantitative prediction is possible. For potent inoculation such as is practised in alu
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