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The present work describes the effect of tempering (T4 and T6) processes on the dry sliding wear properties of ilmenite reinforced aluminum alloy (LM30) composites, prepared through stir casting route. In this process the composites were heated to 540 °C for 0.5–2 h followed by water quenching. Then the samples were first given (a) T4 treatment (natural ageing at room temperature), and in second case (b) T6 treatment (aged at 180 and 250 °C for 4 h before air cooling). Optical microscopy revealed the homogeneous distribution of ilmenite particles and redistributed silicon around the ilmenite in the alloy matrix. Rockwell hardness values suggested the superiority of T6 treated composite samples as compared to T4 treated and untreated samples due to enhanced precipitation of intermetallic compounds viz. Al13Fe4, FeSn2, FeTiSi, and Al3Ti. Similarly, superior wear resistance (against steel disc) of T6 treated composite samples was also observed. A responsible mechanism has also been established with the help of scanning electron microscopy of worn surface and wear debris. Finally, a comparative study revealed the excellent (~ 4.0%) wear resistance (against EN31 steel disc) of T6 treated composite sample as compared to grey cast iron (traditional material) for brake drum applications. [ABSTRACT FROM AUTHOR]

Technology is developed for preparing semifinished sheet of hypereutectic alloys based on the aluminumcerium system intended for operation under conditions of x-radiation. The technology is based on creating a test alloy by casting and subsequent deformation treatment. Two versions of cast billet preparation are considered in the work. Sheet material prepared by rolling these billets exhibits good adaptability and may be used for producing engineering objects. [ABSTRACT FROM AUTHOR]

Diluted alloys of the binary system Ni–Si have been used as target of beam of ions, electrons, neutrons and so on because in this kind of alloy occurs transformations order–disorder, when the temperature is raised. This fact has permitted to evaluate the phenomena associated with the damage induced by irradiation (DII). The results of these works have been employed to understand the behavior under irradiation of complex alloys and to evaluate the reliability of the results of mathematical simulation of the evolution of the DII. The interest in the alloy system Ni-Si has been reborn due to the necessity of developing materials, which have better resistance against the corrosion on more aggressive environments such as those generated on the nuclear power plants or those that exist out of the Earth's atmosphere. Now, a growing interest to use concentrated alloys of this binary system on diverse fields of the materials science has been taking place because up to determined concentration of silicon, a regular eutectic is formed, and this fact opens the possibility to develop lamellar composite material by directional solidification. However, nowadays, there is a lack of fundamental knowledge about the behavior of this type of lamellar structure under aggressive environments, like those mentioned before. Hence, the task of this work is to evaluate the effect that has the irradiation over the microstructure of the concentrated alloy Ni22at%Si. The dendritic region of the hypereutectic alloy consists of an intermetallic phase Ni3Si, whereas the interdendritic region is formed by the alternation of lamellas of solid solution α-Ni and intermetallic phase Ni3Si. Such kind of microstructure has the advantage to get information of the DII over different phases individually, and at the same time, about of the microstructure influence over the global damage in the alloy. The hypereutectic Ni22at%Si alloy was irradiated perpendicularly to its surface, with 3.66 MeV – Ni ions up to 380 dpa at 650°C in a Tandetron linear accelerator. The level of irradiation dose was chosen similar to the irradiation conditions of the next-generation nuclear reactors. The theoretical maximum depth of the DII (maximum depth of damage (MDD)) was calculated as 1.35 µm using the SRIM-2013 program; the laminar microstructure of the eutectic was simulated using the lattice parameters of the eutectic before irradiation. The experimental MDD was 1.47 µm, as determined through transmission electron microscope (TEM) images and the DII was characterized using µX-ray diffraction and TEM. The elimination of cubic phase of the intermetallic Ni3Si, the suppression of lamellae of the α-Ni phase, the generation of dislocation loops and lines, all of these changes generated by the irradiation are clear evidences that the DII was severe. Based on theoretical and experimental evidence, we propose that the amount of phases, alternate of lamellae with different chemical concentrations of silicon and lamellae spatial distribution have a direct relation with the severe evolution of the DII. [ABSTRACT FROM AUTHOR]

The effect of ultrasonic treatment during casting of a hypereutectic Al-Si alloy (Etial 195) containing 18%Si on the microstructure and some mechanical properties has been investigated. For this purpose, a steel mould was placed inside an ultrasonic bath, and molten aluminium alloy at 740°C was poured into the mould. Ultrasound was applied to the casts from the external side of the mould during solidification. Cooling curves were obtained by measuring and recording the temperature of the cast. The samples were subjected to X-ray diffraction analysis and hardness, wear and impact tests. The microstructure of the samples was examined by optical and scanning electron microscopies and investigated statistically with image analysis software. Hardness values increased from 49·8-52·3 to 57·7-61·6 HRB upon ultrasonic treatment during solidification. The application of ultrasonic vibration to the cast from the external side of the mould resulted in modification of the microstructure and improvement in mechanical properties. [ABSTRACT FROM AUTHOR]