ABSTRACT Were characterized microstructurally and mechanically the Ti-6Aℓ-4V alloy obtained through powder metallurgy in an uncontrolled atmosphere, varying the sintering parameters, arose. The samples were compacted in a uniaxial press at 874 MPa, 999 MPa, and 1124 MPa, and sintered without a protective atmosphere or vacuum, at 675 °C, 750 °C, and 850 °C. When sintering the material, the oxides influenced the results due to titanium’s high affinity for interstitial elements, promoting increased density and high hardness values. Based on the results, the treatment carried out at a pressure of 1124 MPa and a temperature of 750 °C showed the highest hardness in the beta phase (β), with a value of 1165.1 HV. In the alpha phase (α), the highest value was 1321.3 HV, presented by the treatment performed at a pressure of 999 MPa and a temperature of 850 °C. The high hardness values observed in the alloy are associated with the reinforcement promoted by the dissolution of Fe atoms. Materials with high hardness values use in the aerospace and biomedical industries, which always look for better mechanical resistance results, thus increasing their products’ useful life and applicability.

RESUMO Foram caracterizadas micro estruturalmente e mecanicamente a liga Ti-6Aℓ-4V obtida através da metalurgia do pó em atmosfera não controlada variando os parâmetros de sinterização. As amostras foram compactadas em uma prensa uniaxial à 874 MPa, 999 MPa e 1124 MPa, e sinterizadas sem atmosfera protetora ou vácuo, nas temperaturas de 675 °C, 750 °C e 850 °C. Ao sinterizar o material, houve influência dos óxidos nos resultados devido à alta afinidade que o titânio tem por elementos intersticiais, promovendo um aumento na densidade e elevados valores de dureza. A partir dos resultados verificou-se que o tratamento realizado na pressão de 1124 MPa e temperatura de 750 °C foi o que apontou a maior dureza na fase beta (β), sendo o valor de 1165,1 HV. Na fase alfa (α), o maior valor foi de 1321,3 HV, apresentado pelo tratamento realizado na pressão de 999 MPa e temperatura de 850 °C. Os elevados valores na dureza observados na liga estão associados ao reforço promovido pela dissolução átomos de Fe. Materiais com elevada dureza possuem uma vasta aplicação nas indústrias aeroespaciais e biomédicas, que buscam sempre por melhores resultados de resistência mecânica, aumentando assim a vida útil e a aplicabilidades de seus produtos.

Concern for sustainable development has provided significant improvements in the development of biodegradable materials. This work aims to evaluate, through a central composite design (CCD), the mechanical properties of cassava starch-based biocomposites manufactured with different compositions of carnauba wax (CW), sisal fiber (SF) and glycerol (G). The biocomposites were obtained by casting method. The tensile strength (TS), modulus of elasticity (ME) and elongation at break (El) for the biocomposites were determined by tensile tests. Representative models were obtained to explain changes in mechanical properties of biocomposites as function of composition variables. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to elucidate interactions between the starch matrix and additives A biocomposite with 7.5% sisal fiber, 10% carnauba wax and 10% glycerol showed the best properties to possible applications.

This work aims investigate the changes on tensile properties of biocomposites obtained by addition of carnauba wax and coconut fibers in a corn starch matrix. The influence of carnauba wax and coconut fibers contents on tensile strength, modulus of elasticity and elongation at break was studied using a response surface methodology. A central composite design based on three levels of carnauba wax content (0, 10 and 20 %) and coconut fibers content (0, 10 and 20 %) was elaborated. Empirical models were obtained to describe these properties as function of coconut fiber and carnauba wax contents. Optical microscopy was carried out to visualize the dispersion and interactions between coconut fibers, carnauba wax and starch matrix in the biocomposites. In presence of carnauba wax, the biocomposite became more compact and with a better interaction between the corn starch-based matrix and coconut fibers reinforcement. It was observed that tensile strength and modulus of elasticity rise with the increase in carnauba wax and coconut fiber contents. Moreover, the elongation at break increases with the addition of coconut fiber, while a decrease in the values of this property occurs with the addition of carnauba wax.