Effect Of Xenon Ion Irradiation On Microstructure And Properties Of Zr Alloy And Austenitic Stainless Steels

Zr alloys and austenitic stainless steels are proposed as candidates for thestructural materials used in unordinary environments such as space or nuclear reactorsdue to their excellent mechanical and irradiation properties. In this paper,200keV Xe~+irradiation tests have been carried out on Zr alloy,1Cr18Ni9Ti and AISI316stainlesssteels by utilizing an ion irradiation facility. X-ray diffraction (XRD), transmissionelectron microscope (TEM), scanning electron microscopy (SEM), nano-indenter,micro-friction and wear testing machine (UMT-3), et al. were used to evaluate theirradiation effects of Xe~+on the materials.The number of vacancy or interstitial cluster defects (black dots) increased withirradiation doses of the three materials. X-ray diffraction line profile analysis(XRDLPA) shows that the order of magnitude of dislocation density in the threematerials remains almost unchanged up to the highest irradiation dose. This suggestedthat Xe~+irradiation at this level did not generate additional dislocation loops throughcollapse of point defects. Ion irradiation induced a small amount of γ-Fe to α-Fe phasetransition in both of the stainless steels and partially amorphization in three materials,and the initial state of the materials had an effect on the γ-Fe to α-Fe phase transition,i.e. the phase transition occurred at low ion doses in incomplete austenitic1Cr18Ni9Tistainless steel, while it took place at high ion doses in the complete austenitic AISI316steel. Implantation-induced (002) texture emerged in Zr alloy and the amount of (002)texture increased with increasing ion doses.The surface mechanical properties of the three materials changed significantlyafter irradiation. The nano-hardness of all the materials was found to increase rapidlywith increasing ion dose till the dose of1×1015ions/cm2, and then gradually saturatewith dose. It was assumed that the irradiation-induced defects acting as barriers todislocation motion lead to hardening of the materials. At the same time, the frictioncoefficients of the irradiation layers of three materials became smaller to some extent,and the ratio of adhesive wear decreased.To clearly observe surface morphology of the materials after irradiation, the verysmooth surface layer of alloys before irradiation were required and it could be obtained by vacuum deposition. The ZrTi alloy thin films were prepared by magnetronsputtering and were irradiated with different dose of Xe+. The irradiation zone of thepolycrystalline ZrTi alloy showed a very interesting phenomenon: low Xe+doseinduced sunken morphology, while high dose Xe+induced swelling morphology. Thissuggested that, surface sputtering and lattice damage near surface occurredsimultaneously during irradiation, and the different morphologies were the result of thesuperposition of the two effects.