Damping Capacity of Cold-Worked Al–Ni Alloys

Abstract

The influence of cold working on the damping capacity and mechanical properties was investigated in Al–Ni alloys containing 0.2 to 12%Ni. The logarithmic decrement δ and the rigidity modulus G were measured by an inverted torsion pendulum method, and the tensile strength σ_t by an Instron-type machine.
In both of the furnace-cooled and water-quenching states the δ was increased to some extent by the Ni addition. By cold working after heat treatment, the δ became considerably higher with increasing reduction in area RA. The alloys cold-worked after furnace cooling was higher in δ than those cold-worked after water quenching; the Al-4%Ni alloy showed the highest δ value of 63×10⁻³ when cold-worked by 95% RA after furnace cooling. The increment in δ by cold working is considered to be due to a remarkable increase in density of dislocations and also to the pinning by the effective amount of the compound Al₃Ni (ε phase) against the motion of dislocations. Cold working after the heat treatments results in a decrease in G and an increase in σ_t. Both G and σ_t increased with increasing Ni concentration, irrespective of the heat treatments and the cold working that followed.