Abstract
This work presents a comparative study of microstructural and electrical properties of polycrystalline material from two different Cu-Ni alloys: Cu-Ni-Pt and Cu-Ni-Al. The first one of them was produced in electric furnace with voltaic arc and the other was produced by powder metallurgy. The microstructure of the samples was studied by optical microscopy, Vickers micro hardness and x rays powder diffraction. Their electrical conductivity was measured with a milliohmeter Agilent (HP) 4338B. Refinements of the crystalline structure of the samples were performed by the Rietveld method, using the refinement program GSAS. The refinement results and Fourier differences calculations indicate that the copper matrix structure presents not significant distortions by the used amounts of the other metal atoms. In both cases a sequence of thermo mechanical treatments was developed with the intention of increasing the hardness maintaining the electrical conductivity of the alloys. The refinements also allowed a study of the dependence of the micro-structure and the thermo mechanical treatments of the samples. Acknowledgments: Mackpesquisa, CAPES.
Highlights
Microstructural characteristics such as the size, type, form and regular distribution of precipitations determine the mechanical resistance in metallic alloys
Products based on copper alloys such as porous material filters, electric friction equipments, contacts and structural parts can be manufactured through the process of powder metallurgy, which have the advantages of making fine grained homogenous structures, forming complicated shapes with close dimensional tolerances and the ability to produce parts with a superior surface finishing [1,2,3,4,5,6,7,8,9,10,11,12,13]
As showed in the optical micrographs of Cu99,33% Ni0,23% Pt0,43% (Figures 1) precipitates are fine and bulk distributed. This influences an increasing of hardness, which resulted in 815,00±0,01 MPa
Summary
Microstructural characteristics such as the size, type, form and regular distribution of precipitations determine the mechanical resistance in metallic alloys. Products based on copper alloys such as porous material filters, electric friction equipments, contacts and structural parts can be manufactured through the process of powder metallurgy, which have the advantages of making fine grained homogenous structures, forming complicated shapes with close dimensional tolerances and the ability to produce parts with a superior surface finishing [1,2,3,4,5,6,7,8,9,10,11,12,13] These advantages reduce or eliminate costly machining processes and allow less scrap loss, compared to other forming methods. Ductility and formability keeping good electric conductivity of these alloys, there have been used special thermal treatments, as well as variations in the chemical composition
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