Behaviour of electrical resistivity in single crystals of Cu-Zn-Al and Cu-Al-Be under stress

Abstract
Electrical resistivity measurement (ER) has been one of the main experimental techniques used in researches that involve alloys with martensitic transformation, due to its susceptibly to detect crystalline structure modifications. In alloys that present shape memory effect, ER is mainly used to study thermal cycling and ageing. Recently, measures of electrical resistance have been coupled to mechanical tests during shape memory effect phenomena. Most of publications using ER at constant temperature in the stress-strain domain was done in polycrystalline alloys of Ti-Ni and Ti-Ni-Cu. In this work, single crystals of copper-based samples were tested at different temperatures to analyse the behaviour of stress and resistivity variation versus strain. During superelasticity test, ER variation presents a linear behaviour and an absence of hysteresis with strain. Mechanical tests are performed at different temperatures and with different orientations of the tensile axis. These results show that the martensite variants present an electrical anisotropy.