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When processed conventionally, aluminum-bronze alloys with high mechanical strength require machining after the raw state of fusion, and the waste (chips), if not reused, can cause problems for the environment and costs for the company. Therefore, this article proposes an alternative for recycling aluminum bronze through the new route via Powder Metallurgy (PM), analyzing the resulting microstructure. This study compares the microstructures of the aluminum bronze derived from extraction (the samples received - SR) and the state after the powder metallurgy (PM) process with the addition of vanadium carbides (VC). The study also analyzes the distribution of VC in the microstructure of the PM composite as well as the influence of the TQ30 heat treatment on this composite. For the PM process, aluminum alloy and bronze chips were ground together with vanadium carbide (VC) in a high-energy mill for 50 hours. The powders obtained were pressed uniaxially (400 MPa) to achieve good compaction. The samples were then sintered (900°C/1h), water quenched (900°C/2h), and subjected to treatment according to the TQ30 standard, which, in addition to the previous treatments, also includes tempering at 500°C for 2 hours (ASTM B150/B150M-12 standard). The microstructure observed in the SR samples was martensitic (in needles), with secondary phases dispersed in the matrix. On the other hand, the microstructure of the PM samples showed equiaxed grains of the alpha phase (κ), as well as the secondary phases kapa (κ) and beta line (β'), in contrast to the needle-shaped microstructure of the conventional melting process. [ABSTRACT FROM AUTHOR]

Aluminum bronze alloy is applied in environments that require materials of high mechanical resistance and wear, such as marine, oil & gas and aerospace ones. This study analyzes the densification of composites based on aluminum bronze with additions of the vanadium (VC) and niobium (NbC) carbides, and the influence of these carbides in the milling efficiency and improvement of the diffusion process between particles to obtain better results for density and porosity. The composites were produced by powder metallurgy from aluminum bronze powders obtained from the mechanical milling process of discarded scraps. The efficiency of the sintering process depends on parameters, such as the time and temperature of sintering, together with the size of the particles obtained from the milling process. This study aimed to obtain and characterize the composites produced by the powder metallurgy route, with NbC and VC addition and to analyze physical properties, such as density and porosity. The powder morphologies, particle sizes and samples sintered were performed by scanning electron microscopy (SEM), X ray diffraction (XRD), laser diffraction analysis and optical microscopy (OM). The results indicate that addition of VC improves the milling efficiency, when compared to NbC addition, since it promotes a greater reduction of the particle size, directly favoring the sintering process. In this case, to achieve similar particle size, twice the milling time was required when NbC was used. The density values achieve ~ 73% of reference material for VC addition and ~ 68% for NbC and porosities varying between 27% and 38%. [ABSTRACT FROM AUTHOR]