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 σt 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 σt. Both G and σt increased with increasing Ni concentration, irrespective of the heat treatments and the cold working that followed.