THE EFFECT OF POROSITY ON THE MICROSTRUCTURAL DAMPING RESPONSE OF 6061 ALUMINUM-ALLOY

The paper reports on the results of a systematic study of the effects of micrometre-sized pores on the damping response of 6061 aluminium alloy. Spray atomization and deposition processing was utilized for the present study as a result of its ability to produce a material with a pre-determined amount of non-interconnected, micrometre-sized pores. The amount and distribution of pores present in the material may be systematically altered through variations in the processing parameters by using this synthesis approach. The damping measurements were conducted on cantilever beam specimens by using free vibration decay and resonant vibration techniques. Experimental results showed that the porosity increased with increasing average pore size; the damping capacity, in terms of logarithmic decrement delta, of the as-spray-deposited 6061 Al alloy, increased from 1.8 to 2.9% as the amount of porosity increased from 4 to 10%. Comparisons show that the damping capacity of the as-spray-deposited 6061 Al alloy is higher than those reported by other investigators using the same alloy but with different processing techniques. The loading damping mechanisms are discussed in the light of data from the characterization of microstructure and damping capacity.