Browsing by Subject "Intermetallic phase"

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    Effect of the surface nanocrystallization on tribological behavior of the Cu based bimetallic materials (CuPbSn)
    (Institute of Physics Publishing, 2019) Gencer G.M.; Yolcu C.; Kahraman F.; Saklakoǧlu N.
    In this study, ultrasonic impact treatment was used to improve the tribological behavior of copper-based bimetallic materials that are used in internal combustion engine bearings and bushes. Bimetallic materials were obtained by coating three different CuPbSn alloys by sintering on the material surfaces of carbon steel substrate. After the sintering process, bimetallic materials were treated by ultrasonic impact process. As a result of the metallographic examination, sintered layers have uniform structure along the cross-section of the bimetallic materials. In addition, it was determined that the porosity of sintered materials decreased after the ultrasonic impact treatment. Due to the grain refinement and work hardening, higher hardness was obtained in the fine-grained layer. The hardness of the ultrasonic impact treated samples always higher than the untreated material. Because of the high surface hardness, ultrasonic impact treated samples showed higher wear resistance. The highest wear resistance was detected in the samples with the highest Sn content. Because Sn and Cu combine to form Cu3Sn intermetallic phase in Cu-Pb alloys and Cu3Sn increases the strength of the Cu-Pb alloys. Thus, increasing the Sn content in the Cu-Pb alloy resulted in the wear resistance increase. Furthermore, the formation of the SnO2 intermetallic phase on the sample surface has a significant effect on the wear resistance increase by preventing adhesion. © 2019 IOP Publishing Ltd.
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    Characterization and Tribological Properties of Novel AlCu4.5SiMg Alloy–(B4C/TiO2/nGr) Quaternary Hybrid Composites Sintered via Microwave
    (Korean Institute of Metals and Materials, 2022) Ayvaz M.
    Abstract: In the future, hybrid aluminum matrix composites, which are the second generation composites, will be replaced by solid reinforced third-generation quaternary hybrid composites in which nano- and micro-scale reinforcement particles are used together. In this study, microwave sinterability of B4C, TiO2 (nm + µm), and nGr reinforced quaternary hybrid composites that had AlCu4.5SiMg alloyed Matrix, and their microstructural and tribological properties after sintering were examined. The proportion of nGr in the composite sample was taken as 0.5 wt%, while B4C and TiO2 were used in three different proportions (3, 9, 12 wt%). After being compressed under 600 MPa pressure, the composite samples were sintered for 60 min at 550 °C by a microwave oven with a power of 2.9 kW and a frequency of 2.45 GHz. It was determined that due to its high microwave absorbency, B4C reinforcement improved the microwave sinterability more compared to TiO2. In XRD analyses, whereas Al4C3 and Al3BC reaction products were not seen as harmful, the intermetallic phase of Al2Cu was detected. It was determined that both friction coefficient and wear resistance increased as the proportion of B4C increased in composite samples. In AlCu4.5SiMg–(12 wt% B4C/3 wt% TiO2/0.5 wt% nGr) quaternary hybrid composites with the highest hardness (97.6 HV), the lowest specific wear rate (0.118 mm3 Nm × 10−3) was detected. Graphic Abstract: [Figure not available: see fulltext.]. © 2020, The Korean Institute of Metals and Materials.