![]() Experimental Procedureįe 67.8Pd 32.2 alloys were prepared from highly pure metal (>99.95 at.%) by arc-melting (SYJ DHL-500 Argon Arc-melting Furnace) under an argon atmosphere at a charge current of 180 A. This work also provides theoretical support and realization possibilities for achieving precise control of the crystallization degree to obtain the desired microstructure of the glass composite to design the desired properties. This investigation introduces new insight into the relationship between the two kinds of glass separately in the noncrystalline matrix and crystalline matrix, which is different from the conventional process from the amorphous phase to crystal after annealing. The changes in diffraction pattern and structure at the microscopic level in TEM observations and the changes in viscoelasticity at the macroscopic level by dynamic mechanical analysis together demonstrate this evolutionary process. We can achieve our main objectives of directly observing the complete process of evolution from the amorphous phase to the strain glass state by an in situ high-resolution transmission electron microscope (TEM), and establishing the link between the two kinds of glass in the severe cold-rolled FePd. Here, Fe 67.8Pd 32.2 alloys, which have been found as strain glass, are cold-rolled up to 90% to create enough large amorphous areas. Among the various strain glass systems that have been reported, such as TiNi-based strain glass, TiNb-based strain glass, and FePd strain glass, FePd strain glass is a good choice due to its ease of processing and feasibility of becoming amorphous by plastic deformation, while TiNi-based strain glass is too difficult to cold-deform, and TiNb strain glass cannot form an amorphous state through cold rolling. However, the lack of direct observation on the evolution of the two kinds of glass makes the transformation path still unclear, so it is difficult to control the degree of recrystallization and the composite structure by controlling the annealing temperature. They offer the possibility to achieve the transformation between metallic glass and strain glass by cold rolling and annealing. In the last decade, related work on the effects of plastic deformation and thermomechanical treatment has been conducted using techniques such as cold rolling, cold drawing, high-pressure torsion, and equal channel angular extrusion. Amorphization of numerous alloys by severe plastic deformation on the bulk arc-melted ingots has been investigated, while most deformation limitations are restricted by the plasticity and cracking. It has been reported that the strain glass state can be achieved by crystallization from the amorphous state through annealing treatment. This work presents the specific pathway and realization possibilities for the design of glass composite materials with enhanced properties. Here, direct observation of the evolution process provides a theoretical basis for achieving precise control of crystallinity to obtain the desired microstructure, while the study of the unusual crystallization process offers a possible way to tailor the mechanical and functional properties through tuning the amorphous and strain glass coexistence. The evolution from the amorphous phase (metallic glass) back to strain glass was directly observed by an in situ high-resolution transmission electron microscope, which revealed that strain nanodomains began to form on the amorphous matrix below the crystallization temperature of the amorphous phase. In this work, the specimen of the almost amorphous state was obtained from the heavy-defects-doping Fe 67.8Pd 32.2 strain glass ingot by arc melting and 90% cold rolling, which were characterized by amorphous packages in X-ray diffraction and amorphous rings in transmission electron microscope diffraction. Previous studies have mostly focused on the properties and structure of single glass however, the link between them has seldom been considered. The amorphous phase is an atomic packing disordered phase, while strain glass is a glassy state with transformation strain disorder in a crystalline matrix, which both bring extraordinary properties to alloys. The amorphous phase and strain glass are both disordered states of solids.
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