Aluminum bronze is a complex group of copper-based alloys that may include up to 14% aluminum, but lower amounts of nickel and iron are also added, as they differently affect alloy characteristics such as strength, ductility, and corrosion resistance. The phase transformations of nickel aluminum–bronze alloys have been the subject of many studies due to the formations of intermetallics promoted by slow cooling. In the present investigation, quaternary systems of aluminum bronze alloys, specifically Cu–10wt%Al–5wt%Ni–5wt%Fe (hypoeutectoid bronze) and Cu–14wt%Al–5wt%Ni–5wi%Fe (hypereutectoid bronze), were directionally solidified upward under transient heat flow conditions. The experimental parameters measured included solidification thermal parameters such as the tip growth rate (V_L) and cooling rate (T_R), optical microscopy, scanning electron microscopy (SEM) analysis, hardness, and microhardness. We observed that the hardness and microhardness values vary according to the thermal parameters and solidification. We also observed that the Cu–14wt%Al–5wt%Ni–5wi%Fe alloy presented higher hardness values and a more refined structure than the Cu–10wt%Al–5wt%Ni–5wt%Fe alloy. SEM analysis proved the presence of specific intermetallics for each alloy.

The Cu-24Zn-6Al-4Mn-3Fe alloy is mainly used for the manufacture of sliding bushings in the agricultural sector due to its high mechanical properties in the cast state. Understanding how the casting thermal parameters affect the microstructure and impact the properties of alloys is fundamental to optimizing manufacturing processes and improving performance during their application. In this study, the Cu-24Zn-6Al-4Mn-3Fe alloy was unidirectionally solidified under non-steady heat flow conditions using a water-cooled graphite base for heat exchange. Seven points were monitored along the longitudinal region of this ingot, and the data to obtain the solidification variables were extracted using an acquisition system. The cooling rates varied from 4.50 °C/s to 0.22 °C/s from the closest to the furthest position from the heat extraction point. The microstructure was analyzed via optical microscopy, scanning electron microscopy and X-ray diffraction in order to characterize the phases and intermetallic elements present in the material. The mechanical properties were evaluated through hardness and microhardness tests throughout longitudinal extension of the solidified part. The results showed an increase in hardness and microhardness with a decrease in the cooling rate, which may be related to the increase in size and the κ phase fraction with a decrease in the cooling rate, as analyzed via optical microscopy and scanning electron microscopy. Furthermore, in all positions, there was no significant change in the amount of the α phase retained, with the matrix being mainly composed of the β phase and a small content of approximately 2% of the α phase.

The properties of the final product obtained by solidification directly result from the thermal variables during solidification. This study aims to analyze the influence of thermal solidification variables on the hardness, microstructure, and phases of the CuAl₆Si₂ alloy. The material was solidified using unidirectional solidification equipment under non-stationary heat flow conditions, where heat extraction is conducted through a water-cooled graphite base. The thermal solidification variables were extracted using a data acquisition system, and temperature was monitored at six different positions, with cooling rates ranging from 217 to 3 °C/min from the nearest to the farthest position from the heat extraction point. An optical microscope, scanning electron microscope (SEM), and X-ray diffraction (XRD) were used to verify the fusion structure and determine the volumetric fraction of the formed phases. The XRD results showed the presence of β phases, α phases, and possible Fe₃Si₂ and Fe₅Si₃ intermetallics with different morphologies and volumetric fractions. Positions with lower cooling rates showed an increased volume fraction of the α phase and possible intermetallics compared to positions with faster cooling. High cooling rates increased the Brinell hardness of the alloy due to the refined and equiaxed β metastable phase, varying from 143 HB to 126 HB for the highest and lowest rates, respectively.

Friction welding (FRW) is an important commercial solid-state welding process in which coalescence is achieved by frictional heat combined with pressure. The objective of this work is to analyze the microstructure and the mechanical behavior of the copper alloy UNS C64200 – bronze-aluminum-silicon, as well as to raise the ideal welding parameters so that there is adequate weldability after process of continuous-drive friction welding. Regarding the analysis of the microstructure, scanning electron microscopy was used to characterize phases. The mechanical properties were evaluated by means of a hardness test of the center of the welded joint, traversing the entire extent of the thermally affected zone. Results show that the UNS C64200 alloy, when subjected to conventional friction welding, behaves satisfactorily in terms of weldability, without the appearance of cracks or defects arising from the temperature characteristic of this process, as well as good hardness with values above the minimum established in norm and higher than the base material.

The mechanical properties of a final product are directly influenced by the solidification process, chemical composition heterogeneity, and the thermal variables during solidification. This study aims to analyze the influence of solidification thermal variables on the microstructure, hardness, and phase distribution of the CuMn11Al8Fe3Ni3. The alloy was directionally and upward solidified from a temperature of 1250 °C. Heat extraction occurred through a water-cooled AISI 1020 steel interface. The thermal variables were recorded using a data acquisition system, with temperature monitored at seven different positions, where cooling rates varied from 13.03 °C/s at the closest position to 0.23 °C/s at the farthest. The Brinell hardness decreased from 199 HB at the highest cooling rate position to 184 HB at the slowest cooling rate position. This indicates that higher cooling rates increase the hardness of the alloy, which can be attributed to the stabilization of the metastable β phase with refined and equiaxial grains due to iron addition. Vickers microhardness was observed in regions subjected to slower cooling (244 HV) compared to faster cooling regions (222 HV). Therefore, the correlation between solidification thermal variables and alloy properties provides valuable insights into the relationship between microstructure and the properties of the CuMn11Al8Fe3Ni3 alloy.