Simultaneous measurements of photoemission and morphology of various Al alloys during mechanical deformation

We report simultaneous measurements of strain and photoelectron emission from high purity Al (1350), Al-Mg (5052), Al-Mn (3003), Al-Cu (2024), and Al-Mg-Si (6061) alloys under uniaxial tension due to pulsed excimer laser radiation (248 nm). The emission of low-energy photoelectrons is sensitive to deformation-induced changes in surface morphology, including the formation of slip lines and slip bands. Alloy composition and surface treatment significantly influence the photoemission during deformation. Surface oxide enhances the signal-to-noise level during photoemission measurement. In the early stage of deformation (strain <= 0.04), photoemission intensity increases gradually in a nonlinear fashion. While subsequent photoemission increases almost linearly with strain until failure in samples with thin oxide layer (similar to 31 A), there are two linear segments of photoemission for the samples with oxide of 45 A. The onset of strain localization corresponds to the intersection point of two linear segments, usually at a strain of 0.08-0.20. A constitutive model incorporating microstructure evolution and work hardening during tensile deformation is proposed to qualitatively interpret the growth of the photoemission as a function of strain. Photoemissions from various alloys are interpreted in the light of surface treatment, work function, composition, and microstructural development during deformation. (c) 2006 American Institute of Physics.