Anomalous resistivity change in β brass by annealing below 523K

摘要

Two sorts ofβ single phase and anα + β two phase Cu- Zu alloys were annealed below 523K.Detailed investigation on anomalous resistivity increase has cleared following facts. The resistivityincrease is occured by annealing below 473K, even under coexistence ofα phase. During holding atroom temperature, the once increased resistivity gradually decreases to nearly same value beforeannealing. Therefore, the increase in resistivity is reversible and amount of increase is determined byannealing temperature. The amount of resistivity increase becomes larger with elevated annealingtemperature up to 423K, in opposite sence to G. P. zone formation in aluminium alloys. From theseobservations, this increase can not be interpreted by any precursor of martensitic transformation, andit should be caused by increase in concentration of "wrong atom", as previous predictions. However,the reason why this phenomenon occurs is the remaining problem. As a subproduct, it is confirmedthat the resistivity ofβ phase shows negative dependence on Zn concentration or, the resistivitydecreases with increasing Zn content, represented byρ{sub}(β77)Ωm = 97.26 -1.765C{sup}(zn)/at%.