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In this work, the mechanical properties and microstructural features of an AISI 304L stainless steel in two presentations, bulk and fibers, were systematically studied in order to establish the relationship among microstructure, mechanical properties, manufacturing process and effect on sample size. The microstructure was analyzed by XRD, SEM and TEM techniques. The strength, Young’s modulus and elongation of the samples were determined by tensile tests, while the hardness was measured by Vickers microhardness and nanoindentation tests. The materials have been observed to possess different mechanical and microstructural properties, which are compared and discussed.

Many studies have been done using waste short plastic fibers to reinforce concrete. The objective of this investigation is the development of a novel arrangement of reinforcement with continuous recycled PET fibers, to enhance the mechanical properties of concrete beams. The novel arrangement consists of continuous PET fibers of the same length as concrete beams, placed in the mold, fixed and prestressed prior to casting the concrete. Due to the fact that in previous investigations on concrete reinforced with PET fibers, these fibers have been used in a short, dispersed way; it is of interest to compare the effect of the novel arrangement of continuous fiber reinforcement with the typical short, discontinuous fiber reinforcement. Thus, in this paper concrete beams were reinforced using both fiber arrangements. The mechanical behavior of reinforced concrete samples were evaluated and compared by bending tests. The results showed a better performance of the continuous PET fiber reinforcement than that of the short, discontinuous one; the continuous PET samples presented a great increase in the concrete properties in 150% the maximum load in bending. Before testing the concrete composites, recycled PET fibers were mechanically and structurally characterized by FTIR, DSC and tensile tests.

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The mechanical alloying technique was employed to produce series of high entropy alloys, combining in equiatomic percentage Al, Co, Cr, Cu, Fe, Mo, Ni and Ti. Milling times were 0, 10, 20 and 30 h, and experiments were performed in a high energy ball mill (SPEX-8000M) under argon atmosphere. The structural and microstructural changes due to mechanical alloying process were studied by X-ray diffraction and electron microscopy. Although there is the presence of pure elements with HCP crystalline structure, the XRD patterns of as-milled powders revealed the presence of a mixture of nanocrystalline solid solution with FCC and BCC structure phases. The hardness of the powder samples was evaluated by Vickers microhardness testing. The average microhardness values indicate that the alloy with the greatest hardness is the NiCoAlFeMoCr.

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