Development of a high-strength high-conductivity Cu−Ni−P alloy. Part II: Processing by severe deformation

Abstract

Deformation microstructures during large-strain plastic working were studied in the pure Cu and Cu-1.5%Ni-0.3%P alloy, the original microstructures of which have been detailed in our companion publication. Microstructural changes depended significantly on the initial structural state. Solution-treated and low-temperature (400°C) aged samples were characterized by rapid strain hardening with early deformation followed by steady-state-like behavior at large strains. Such a rapid increase in hardness might be responsible for the development of deformation twinning and microshear banding at relatively small strains. Deformation textures in these samples were associated with a large fraction of brass orientation, i.e., {011},211.. On the other hand, the samples aged at elevated temperature (600°C) showed gradual continuous strain hardening upon cold working within the studied strain range. Twinning and microshearing were remarkably delayed, and the texture had no unique preferential orientation. After severe deformation, the samples aged at 600°C demonstrated hardness of ;2500 MPa and electroconductivity .50% IACS.

Ultrafine Grain Formation in Ferritic Stainless Steel during Severe Plastic Deformation

“…Large shear strains were shown to result in a rapid increase of misorientations among strain-induced sub-boundaries. [16,[21][22][23][24][25] However, regulations of such a mechanism of microstructure evolution are not perfectly understood. The final grain size that evolved in strain-induced submicrocrystalline structures can be reduced by decreasing the deformation temperature.…”

Ultrafine Grain Evolution in a Cu-Cr-Zr Alloy during Warm Multidirectional Forging

“…This might result from high density of DDWs evolved in the ST+AT samples at preceding strains. These DMBs and DDWs serve as nucleation sites for ultrafine DRX grains during the MDF [6,11]. Therefore, the high density of DDWs in the ST+AT samples results in superior kinetic of the DRX development.…”

Grain refinement in a Cu–Cr–Zr alloy during multidirectional forging

“…The strength of copper can be significantly increased by cold working [3][4][5], grain refinement [6][7][8][9][10][11], and the precipitation of nanoscale dispersoids [2,[11][12][13][14][15]. However, strengthening leads to a pronounced decrease in the electrical conductivity, due to increase in the dislocation density, grain boundaries, dispersoids, and solutes, which increase the scattering of conducting electrons [1].…”

“…Recently, a promising approach for strengthening of Cu-Cr-Zr alloys while retaining their electric conductivity at a sufficiently high level of 80% IACS was developed [15][16][17]. This approach involves a large strain deformation followed by a final aging that enables the formation of an ultrafine-grained structure stabilized by nanoscale precipitations.…”

“…This approach involves a large strain deformation followed by a final aging that enables the formation of an ultrafine-grained structure stabilized by nanoscale precipitations. The contributions of dispersoids and grain boundaries to the reduction of electrical conductivity are the lowest among all the aforementioned defects [1,[13][14][15]. At the same time, dispersoids and grain boundaries provide an ultimate tensile strength of 600 MPa or higher through dispersion hardening and grain size strengthening [11,16].…”