Defe Ct S in Som E Hy Droge Nate D M Et a Lli C M Ate Ri Als Studied by Positr on S

The measurements of angular correlation of annihil ati on radiation and p ositron lif etime w ere perf ormed to study defects in commercial stainless steel and nickel subj ected to deformation and electron irradiatio n. I t follow s from variation of S -parameter derived from angular correlation of annihilation radiation spectra that hydrogen charging of Fe{ Cr{N i{Mn austenite steel results in app earance of modest amount of vacancies w hich agglomerate into small clusters during anneali ng at low temp eratures. Electron irradiatio n pro duces much more defects, so that subsequent hydrogenation does not add much to their concentration. T he maj or part of defects anneals out graduall y to 700 K . T he residual part is preserved up to 950 K . T his fact testi Ùes to b onding state of vacancies. N ickel of 3N purity w as prepared in three initial states, i.e. coldroll ed and hydrogenated b efore and af ter deformation. In an initia l state all samples contain, along w ith simple defects, vacancy clusters. T heir size and concentration are much larger in hydrogenated samples, as compared with merely coldrolled one. A nnealing above 400 K causes grow th of cluster size and decrease in their concentration. A t 500 K clusters are observed to disapp ear in coldrolled sample, while in the sample hydrogenated af ter deformation they survive to 600 K . PACS numb ers: 78.70 Bj