Structural, electrical, and mechanical characteristics of proton beam irradiated Al5086 alloy

Al5086 alloy specimens were irradiated in a vacuum ~10−6 mbar with 2 MeV proton beam (200 nA) for different exposure times in the range 10–50 min (dose range: 0.35×1015–1.75×1015 p/cm2). Surface hardness was found to increases on irradiation for 10 min, and later on it decreases with the increase in exposure time. The electrical resistivity of the specimens measured by four-point probe technique was also found to follow the same pattern. The observed behavior has been explained in terms of relative contribution of two processes, namely defects formation and heat generation due to proton–material interaction. Structural characterization of the specimens was done by X-ray diffraction technique. Both surface hardness as well as electrical resistivity of un-irradiated and irradiated specimens is found to decrease with the increase in X-ray crystallite size. Moreover, the surface hardness follows the Hall–Petch relation, which indicates that crystallite boundaries progressively impede the motion of dislocations as the crystallite size gets smaller.