Internal friction in quenched B phase CuZn and CuZnAl alloys.

Abstract

The ordering reaction ín 3 CuZn alloys cannot generally be suppressed by quenchíng (l). However, some short range disorder can be retained on quenchíng as reported by several investiga tors (2-5). Notably, Clarebrough (2) observed an internal friction peak in g CuZn at 70°C that decayed with time. Similar aging effects subsequent to quenchíng have also been noticed while measuring the electrical resistivity (3~5) and the martensitic transformation temperatures (5) of these alloys. Thus Koczak et al (4) detected a small recovery stage between -50°C and 0°C in addition to the main recovery stage between 20°C and 50°C from isochronal annealing curves of resistivity in quenched or electron irradiated Cu-48.4 wt^ Z n . The activation energy associated with this small recovery stage was reported to be 30 to 40 kj/mole. Koczak et al concluded from their results that a point defect exists below 0°C which is mobile and causes atomic interchange. The intention of the present study is to obtain more details concerning these point defects, part¡culary as quenchíng and subsequent aging strongly influence the martensitic transformation (5). To this end, internal friction measurements below room temperature were carried out in 6 CuZn and g CuZnAl single crystals, and the results are reported in this note.