Effects of hot-rolling on secondary electron yield properties of Cu-2.7Be alloy

Abstract

The effects of hot-rolling on the secondary electron property evolution of activated Cu-2.7Be sheets were investigated in this study. The microstructures of both pristine and activated Cu-2.7Be alloys subjected to different hot-rolling temperatures were characterized. Their phase compositions were found to comprise an α matrix and eutectoid phases ( α + γ ). Using electron back-scattered diffraction, the initial average grain size ( d 0 ) was found to vary from 6.45 μ m to 15.63 μ m as the hot-rolling temperature increased from 680 °C to 830 °C. Scanning electron microscopy and X-ray photoelectron spectroscopy studies of the activated Cu-2.7Be sheets revealed that the amount of BeO increased with a decrease in the average grain size, resulting in the enhancement of the peak secondary electron emission yield. Scanning Kelvin probe force microscopy measurements confirmed that the main contributor to the BeO enhancement was the α matrix, while transmission electron microscopy analysis showed that BeO formed preferentially from sub-grain boundaries, indicating the importance of grain boundaries for BeO formation. Moreover, the peak secondary electron yield ( δ m ) exhibited a linear relationship with d 0 −0.5 similar to the Hall-Petch relation. The results in this study will be important for enhancing the secondary electron yield of Cu-Be dynodes used in photomultiplier tubes and electron multipliers. • The peak secondary electron yield (SEY)of Cu-2.7Be alloys after activation are inversely proportional to the rolling temperature. • The lower the deformation temperature is, the more BeO content is after activation. • The matrix contributes more to the increase of SEY than eutectoid structure.