Caracterização da liga amorfa Cu36Ti34Zr22Ni8 processada termomecanicamente

• Autor(a) principal: Medeiros, Bruno Bellini
• Data de Publicação: 2015
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UFSCAR
• Texto Completo: https://repositorio.ufscar.br/handle/ufscar/744
• topic: Metalurgia; Metais amorfos; Consolidação a quente; Radiação sincrotrônica; ENGENHARIAS::ENGENHARIA DE MATERIAIS E METALURGICA

Glass forming ability (GFA) is one of the big issues to obtain large bulk metallic glasses, which are composed of three or more elements. Regardless of an increasing theoretical understanding of glass formation, taking a look in the vast multidimensional compositional space, the increasing number of elements is concerning. How many? How long will we take searching good-inexpensive compositions for applying in the near-net-shape processing predestined to BMGs? Here, we present the results of Cu36Ti34Zr22Ni8 alloy processed either by melt cooling or milling, which was subsequently hot compacted. After the processing by two routes was verified that the GFA of ribbons was poor and for powders and bulk samples was improved by increasing of 96 K in the crystallization temperature (Tx) After analysis by transmission electron microscopy, corrosion and syncrotron light was observed phase separation in the 3 materials. Phase separation can decrease, that can explain the ribbons behavior. However, after synchrotron data processing, including Reverse Monte Carlo (RMC) simulation was observed a GFA improvement (~10 times greater than in the ribbons) due to an increased interaction between small-large atoms. Evidently this behavior was attributed to differences in the processing. This finding indeed proffers a brand-new viewpoint of the metal's amorphous state, and has implications in the understanding of the structure as being as well a consequence of the processing. This will open a new highway toward the reuse of already developed interesting alloys, which will have the same composition but with a significant improvement in the GFA.