A new ultrahigh strength Cu–Ni–Si alloy

• Published in: Intermetallics 2013-11, Vol.42, p.77-84
• Main Authors: Lei, Q., Li, Z., Xiao, T., Pang, Y., Xiang, Z.Q., Qiu, W.T., Xiao, Z.
• Format: Article
• Language: English
• Subjects: Alloy development; Alloying; B. Alloy design; B. Precipitates; BERYLLIUM COPPERS; C. Melting; C. Thermomechanical treatment; COPPER ALLOYS (40 TO 99.3 CU); Copper base alloys; D. Microstructure; G. Automotive uses; HARDNESS; MECHANICAL PROPERTIES; PRECIPITATES; Precipitation; PROPERTIES; Spots; Strength
• ISSN: 0966-9795
• DOI: 10.1016/j.intermet.2013.05.013

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 β-Ni3Si phase precipitated in the initial stages ageing process, with further increasing the ageing time, β-Ni3Si, and δ-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 δ-Ni2Si precipitates. The crystal orientation relationship between matrix and precipitates is that: (111¯)cu//(111¯)β//(02¯1)δ;[112]cu//[112]β//[012]δ. The tensile strength, yield strength and elongation of designed alloy are 1090 MPa, 940 MPa and 3.5%, respectively. [Display omitted]