Desenvolvimento de novas ligas de alta entropia à base de TiZrNbTaMo/Mn para potencial aplicação biomédica
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Data
2022-02-17
Autores
Torrento, Jhuliene Elen
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Nos últimos anos, ligas de alta entropia (HEAs) têm sido desenvolvidas e reconhecidas pela sua elevada resistência mecânica, ductilidade e resistência à corrosão, o que têm atraído a atenção para utilização na área biomédica. Contudo, as HEAs já desenvolvidas não possuem propriedades adequadas para a utilização como biomateriais. Este projeto objetiva caracterizar a estrutura cristalina, microestrutura e as propriedades mecânicas de uma nova liga biomédica com alta entropia composta por elementos não tóxicos (Ti, Nb, Zr, Ta e Mn), para possível aplicação como implantes biomédicos. Para desenvolvimento do estudo, foram produzidas amostras das ligas TiZrNbTaMn e TiZrNbTaMo em proporções não equiatômicas. As amostras foram fundidas por fusão a arco voltaico. Depois de fundidos, os lingotes foram submetidos a um tratamento térmico de homogeneização a 1000 ºC por 12 horas, com resfriamento lento ao ar. Em seguida, foram realizados tratamentos térmicos de envelhecimento a 300 ºC, 400 ºC e 500 ºC por 6 horas, com resfriamento rápido em água. A caracterização das amostras foi feita por medidas de densidade, EDS, mapeamento químico, DRX, microscopia óptica, microscopia eletrônica de varredura, microscopia eletrônica de transmissão, medidas de módulo de elasticidade, medidas de microdureza Vickers, ensaios de biocompatibilidade, ângulo de contato e corrosão. As caracterizações químicas indicaram boa qualidade das amostras produzidas. A caracterização estrutural indicou uma predominância de estrutura cristalina CCC e precipitação de uma fase secundária HC. A caracterização microestrutural exibiu a formação de estruturas dendríticas na condição bruta de fusão. Após os tratamentos térmicos, as ligas apresentaram grãos irregulares e a presença de estruturas aciculares. As medidas de módulo de elasticidade e microdureza apontaram baixo módulo de elasticidade e elevada microdureza das ligas produzidas em relação a alguns biomateriais comerciais. Os testes de biocompatibilidade indicaram baixa citotoxicidade e superfície favorável para a adesão celular, com boa resistência a corrosão. Os resultados apontam bons resultados das ligas estudadas comparado com ligas biomédicas convencionais, evidenciando um bom potencial para prosseguimento dos estudos visando aplicação como um biomaterial.
In the last years, high entropy alloys (HEAs) have been developed and recognized for their high strength, ductility, and corrosion resistance, which has attracted attention by the biomedical industry. However, the properties of the developed HEAs do not match with the requirements for use as a biomaterial. This project aims to characterize the crystalline structure, microstructure, and mechanical properties of a novel biomedical HEA composed of non-toxic elements (Ti, Nb, Zr, Ta, and Mn), for possible application as biomedical implants. For this study, TiZrNbTaMn and TiZrNbTaMo alloys were produced in non-equiatomic proportions. The samples were cast by arc-melting. After melting, the ingots were subjected to a homogenization heat treatment at 1000 ºC for 12 hours, with slow cooling in the air. Then, aging treatments were performed at 300 ºC, 400 ºC, and 500 ºC for 6 hours, with water cooling. The samples were characterized by density, EDS, chemical mapping, XRD, optical microscopy, scanning electron microscopy, transmission electron microscopy, elastic modulus measurements, Vickers microhardness measurements, biocompatibility, contact angle, and corrosion tests. The chemical characterizations indicated good quality of the produced samples. Structural characterization indicated a BCC crystal structure and precipitation of a secondary HCP phase. The microstructural characterization showed the formation of dendritic structures in the as-cast condition. After the heat treatments, the samples showed irregular grains and the presence of acicular structures. The selected mechanical measurements indicated low elastic modulus and high microhardness of the studied samples in relation to some commercial biomaterials. Biocompatibility tests indicated low cytotoxicity and a favorable surface for cell adhesion, with good corrosion resistance. The samples exhibited better combination of properties than some commercial metallic biomaterials, having a great potential for further studies targeting their use as a biomaterial.
In the last years, high entropy alloys (HEAs) have been developed and recognized for their high strength, ductility, and corrosion resistance, which has attracted attention by the biomedical industry. However, the properties of the developed HEAs do not match with the requirements for use as a biomaterial. This project aims to characterize the crystalline structure, microstructure, and mechanical properties of a novel biomedical HEA composed of non-toxic elements (Ti, Nb, Zr, Ta, and Mn), for possible application as biomedical implants. For this study, TiZrNbTaMn and TiZrNbTaMo alloys were produced in non-equiatomic proportions. The samples were cast by arc-melting. After melting, the ingots were subjected to a homogenization heat treatment at 1000 ºC for 12 hours, with slow cooling in the air. Then, aging treatments were performed at 300 ºC, 400 ºC, and 500 ºC for 6 hours, with water cooling. The samples were characterized by density, EDS, chemical mapping, XRD, optical microscopy, scanning electron microscopy, transmission electron microscopy, elastic modulus measurements, Vickers microhardness measurements, biocompatibility, contact angle, and corrosion tests. The chemical characterizations indicated good quality of the produced samples. Structural characterization indicated a BCC crystal structure and precipitation of a secondary HCP phase. The microstructural characterization showed the formation of dendritic structures in the as-cast condition. After the heat treatments, the samples showed irregular grains and the presence of acicular structures. The selected mechanical measurements indicated low elastic modulus and high microhardness of the studied samples in relation to some commercial biomaterials. Biocompatibility tests indicated low cytotoxicity and a favorable surface for cell adhesion, with good corrosion resistance. The samples exhibited better combination of properties than some commercial metallic biomaterials, having a great potential for further studies targeting their use as a biomaterial.
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Palavras-chave
Biomateriais, Ligas de alta entropia, Microestrutura, Propriedades mecânica, Corrosão, Biocompatibilidade, Materiais biomédicos, Ligas, Biomaterials, High entropy alloys, Microstructure, Mechanical properties, Corrosion, Biocompatibility