Effects of Impurities on Microstructural Evolution and Deformation Process of Ion-Irradiated V–Cr–Ti Alloys

Abstract

Microstructural examination and microhardness test were carried out for unalloyed vanadium, V-5Ti, V-4Cr-4Ti alloys irradiated with 4 MeV Cu ions at temperatures from 200 to 600 C. In order to investigate the impurity effect, high purification technique was used. Impurity effects can be seen in the nucleation and growth processes of voids in unalloyed vanadium and those of Ti(OCN) precipitates in V-5Ti. The changes in microstructure due to interstitial impurity could not be seen in V-4Cr-4Ti after the irrodiations below 300 C. The effect of impurity for irradiation hardening in ion-irradiated V-4Cr-4Ti alloys could be seen at 400 C, but it could not be seen at 200 and 300 C. On the other hand, dislocation channels were observed at 200 and 300 C, and the total length of dislocation channels became larger as the impurity level increased. It can be considered that there was practically no correlation between irradiation hardening and total length of dislocation channels due to impurity effects.

Effect of cold work deformationon irradiation hardening of vanadium alloys

“…The black contrast zone with a spherical shape as denoted by the yellow dotted arrows shows a similar As shown in previous papers, Ar-filled bubbles were observed in ODS steels after mechanical alloy in Aratmosphere [51]. Also, it was reported by Fukumoto that small voids were observed in vanadium alloys after irradiation with Cu ions at 400 • C, and after reducing the interstitial impurity by the Zr-treatment method, void formation could be inhibited, indicating interstitial impurity-assisted vacancy clustering [52]. However, due to the limitation of the TEM resolution and low atom concentration in the bubbles, the precise determination of the nature of the bubbles is a tough challenge.…”

Friction Stir Processing of Particle Reinforced Composite Materials

“…Unfortunately, welded structures are more prone to fracture because of the presence of residual stresses, non-equilibrium microstructure, cracks and other metallurgical defects. Vanadium alloy joins produced using gas tungsten arc, laser and electron beam welding have been found to have low fracture toughness due to the embrittlement of heat affected zone [ 80 , 81 ]. It is obvious that current practices used to process vanadium alloy joints are not good enough for engineering applications.…”

Microstructure and texture evolution during accumulative roll bonding of aluminium alloy AA5086

“…This difference can be explained on the basis of respective starting orientations. During the tensile deformation of polycrystalline aluminium, the grains with <001> tensile axis orientation showed equiaxed cell structure with crystallographic dislocation boundaries parallel to the primary slip planes [49][50][51]. On the other hand, layered cell structure with non-crystallographic (dislocation walls at a large angle with the primary slip plane) dislocation boundaries forms in grains with <111> tensile axis.…”