A new ultrahigh strength Cu-Ni-Si alloy

A new ultrahigh strength Cu-6.0 Ni-1.0 Si-0.5 Al-0.15 Mg-0.1 Cr alloy has been developed by alloying design and thermal mechanical treatment. Electrical conductivity, mechanical properties of the designed alloy such as hardness, tensile strength, yield strength, elongation and anti-stress relaxation resistance were tested. The mechanical properties and electrical properties of designed alloy were comparable to those of Cu-Be alloys, and its anti-stress relaxation resistance even was better than that of Cu-Be alloys at evaluated temperature. Microstructure observation revealed that beta-Ni3Si phase precipitated in the initial stages ageing process, with further increasing the ageing time, beta-Ni3Si, and delta-Ni2Si phase precipitates appeared and contributed to the ultrahigh strength by Orowan strengthening. The satellites spots around diffraction spots of Cu matrix symmetrically in [112](Cu) zone crystal axis have been determined, resulting that satellites spots are from the electron diffraction of delta-Ni2Si precipitates. The crystal orientation relationship between matrix and precipitates is that: (11 (1) over bar)(cu)//(11 (1) over bar)(beta)//(0 (2) over bar1)(delta); [112](cu)//[112](beta)//[012](delta). (C) 2013 Elsevier Ltd. All rights reserved.