Effect on mechanics properties and microstructure of molybdenum by high intensity pulsed ion beam irradiation

Abstract

In this paper, high intensity pulsed ion beam (HIPIB) of 85% Cn+ + 15% H+ was used to irradiate crystalline molybdenum. Before and after irradiation, the surface structure and mechanical properties were studied with different irradiation times and energy densities. After HIPIB irradiation, stress was generated inside the molybdenum. As the energy density increases, the thermal effect which was enhanced apparently causes a preferred orientation in the molybdenum. When the energy density reaches 1.6–2.5 J/cm2 with 3 pulses, craters and cracks appear on the surface of molybdenum. Besides, the α-Mo2C phase formed in the near-surficial region of molybdenum is beneficial to the hardness increasement. After HIPIB irradiation, the ratio of average hardness (Hirr/Hunirr) and Nix-Gao model show that the macro hardness of molybdenum decreases with the increase of pulse number and energy density. Compared with the effect of ion implantation on hardness improvement, the annealing effect of HIPIB thermal irradiation plays a more important role in the reduction of molybdenum hardness. The hardness of the molybdenum decreases under the combined action.