Effect of MeV ion irradiation on the coefficient of thermal expansion of Fe-Ni Invar alloys: A combinatorial study

摘要

The effect of low-dose MeV ion irradiation on the thermal conductivity and coefficient of thermal expansion (CTE) of Fe-Ni alloys has been studied over the entire composition range using a combinatorial method. With our experimental precision of + - 5, the thermal conductivity of Fe-Ni alloys is unchanged by 2.3 MeV Ar~+ irradiation at a fluence of 1.2 X 10~(14) ions cm~(-2). The CTE of Fe-Ni Invar alloys with Ni concentrations between 30 and 37 at. increases significantly upon 2.3 MeV Ar~+ irradiation. At the Invar composition of Fe_(65)Ni_(35), the CTE increases from 0.5 X 10~(-6) K~(-1) before ion irradiation to 4.3 X 10~(-6) K~(-1) after irradiation for an ion fluence of 1.2 X 10~(14) ions cm~(-2) or, equivalently, 0.1 displacements per atom. We attribute this increase in CTE to changes in atomic short-range order created by ion irradiation.