Effects of grain size from micro scale to nanoscales on the yield strain of brass under compressive and tensile stresses using a Kelvin probing technique

Effects of grain size on the yield strain of brass (70–30), respectively, under tensile and compressive stresses were investigated using a Kelvin probe, a highly sensitive instrument for measuring the electron work function (EWF) of materials. The average grain size under study varied from 20 nm to 80 μm. The nanocrystalline structure was generated by sandblasting followed by recovery treatment. Results of the EWF measurement demonstrated that the yield strain differed as applied stress changed from tensile to compressive. The magnitude of compressive yield strain is larger than that of tensile yield strain. It was observed that with a decrease in grain size, the difference in magnitude between the compressive yield strain and the tensile yield strain decreased. The mechanism responsible for the difference in yield strain and the effect of grain size on the yield strain are discussed.