Effect of Al on Microstructure and Properties of Cu−Be−Ni Alloy Processed by Thermo-Mechanical Treatment

• • The Cu−0.3Be−2.0Ni−0.2Al alloy achieves a tensile strength of 881 MPa and hardness of HV 268 after 70% cold rolling and aging at 450 °C for 60 min, representing a 4.9% strength increase over the Al-free alloy (840 MPa). This matters industrially because it enables down-gauging of components in precision instruments and connectors without sacrificing mechanical integrity. • • Thermo-mechanical treatment yields a 13% hardness increase and a 6.8% conductivity increase in the Al-modified alloy compared to conventional aging, directly reducing energy losses in high-frequency electrical connectors and extending service life under cyclic loading. • • The Al-free alloy retains a higher conductivity of 50% IACS versus 47% IACS for the Al-containing alloy, a 6% relative reduction. For applications where conductivity is the primary metric, such as high-current carrying springs, this trade-off must be weighed against the 4.9% strength gain. • • The phase transformation sequence γ″→γ′→γ in the Cu−0.3Be−2.0Ni alloy is altered by Al addition to include Ni3Al co-precipitation, which pins grain boundaries and dislocations more effectively. This microstructural control is critical for extending fatigue life in aerospace and petrochemical valve components.