The effect of crater creation on the fatigue strength and corrosion resistance of refractory alloys irradiated by high-power pulsed ion beams

Abstract

The influence of high-power pulsed ion-beann (HPPIB) irradiation and various methods of preliminary surface treatment on crater creation was examined with the use of Auger electron spectroscopy, X-ray diffraction analysis, and scanning electron microscopy. The crater distribution density, sizes and shape, along with the microhardness and chemical composition Inside and out side craters were determined. The targets from refractory alloys treated with HPPIBs under the Irradiating conditions (Ion energy - E=300 keV; pulse duration - т=50 ns; the ion current density in a pulse - j=120-220 A/cm^, the number of pulses - n=1-100; Temp accelerator), when crater creation takes place on the surface of refractory alloys, were subjected to the fatigue and corrosion tests. It was determined that crater creation results in the catastrophic fracture of the irradiated samples during a cycle load In air at operating temperature. In this case the nucleation of fracture lies into the locality of formed craters. Furthermore, corrosion tests have shown that titanium alloys Irradiated by HPPIBs under the condition of crater creation were subjected to the pitting corrosion mechanism in seawater at thermocycling from 500 to 20 °C. According to the fatigue and corrosion test results, the adjoinity and dent-shape craters are the most dangerous under the cycle load.