Microstructure and Mechanical Properties of Copper, Nickel and Ternary Alloys Cu-Ni-Zr Obtained by Mechanical Alloying a
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Microstructure and Mechanical Properties of Copper, Nickel and Ternary Alloys Cu-Ni-Zr Obtained by Mechanical Alloying and Hot Pressing C. Martínez1*, F. Briones2, P. Rojas1, S. Ordoñez3, C. Aguilar2, D. Guzmán4 1
Escuela de Diseño, Universidad Adolfo Ibáñez, Diagonal Las Torres 2640, Santiago, Chile Departamento de Metalurgia, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso, Chile 3 Departamento de Metalurgia, Universidad de Santiago de Chile, Av. Libertador Bernardo O`Higgins 3363, Santiago de Chile. 4 Departamento de Metalurgia, Universidad de Atacama, Av. Copayapu 485, Copiapó, Chile *Email: [email protected] 2
ABSTRACT Elemental powders of Cu and Ni, binary alloys (Cu-Ni and Cu-Zr) and ternary alloy (CuNi-Zr) obtained by mechanical alloying and uniaxial compaction hot microstructure and mechanical properties were investigated. The alloys studied were: pure Cu, pure Ni, binary alloys (Cu-Ni; Cu-Zr) and ternary alloys (Cu-Ni-Zr) under the same mechanical milling and hot pressing conditions. The samples were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM); the mechanical properties were studied by compression tests and hardness in Vickers scale (HV0.5) on polished surfaces at room temperature. According to XRD results, hot pressing process crystallite size increase and microstrain decreases in the compact samples due to the release of crystalline defects. The compacted samples have porosity of approximately 20%. The milling powder samples have a higher hardness than the unmilled samples, this because during milling crystal defects are incorporated together with the microstructural refinement. Ternary alloy is the one with the highest hardness of all systems studied, reaching 689 HV0.5. In compression tests determined a strain 5 %, Zr-containing samples become more fragile presenting the lowest values of compressive strength. In contrast, samples of Ni and CuNi binary alloy are more resistant to compression. INTRODUCTION Nanostructured materials are of great interest due to their improved properties, especially chemical and mechanical, such as high corrosion resistance [1], fracture strength [2-4], wear resistance [5, 6], compared to its micro- or macrostructured counterpart. The differences in the properties of these materials are produced by the major number of interfaces that can act as barriers to slip dislocations, which are able to control and reduce the propagation direction of the cracks, to increase the hardness and toughness. Metal glasses exist since 1960, Clement et al. [7] studied amorphous Au75Si25 by rapid quenching synthesize, BMG materials have since become one of the most popular topics in the field of materials science at present, due to their properties as excellent wear resistance, high strength to corrosion, high hardness, and Young modulus low of and high resistance to fatigue [8-11].
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