Abstract
The internal friction and the Young’s modulus of Cu-Al alloys with 0 to 16 weight par cent of aluminium were measured at room temperature using free transversal vibration of about 1000 cycles/sec. An alloy of martensitic structure has an extremely high internal friction (1−2×10−3), which is independent of various pretreatments of specimens, such as casting, forging, annealing at 620°, and quenching from 800°, seemingly remaining constant over the frequency range 300 to 7000 cycles/sec and showing a very low Young’s modulus (7.5−8.8×103 kg/mm2).The internal friction of the alloy consisting of α and β′ phases is governed by the quantity of the martensitic structure. The internal friction of α-phase depends largely on the pretreatment of the specimen; its value increases with an elevation of the quenching temperature, and decreases with increasing concentration of aluminium according to a power fuction. The γ-phase has a very low internal friction, and a high Young’s modulus.
