Nanostructured surfaces

Temperature range of helium retention from ferritic–martensitic
steel implanted helium at RT

O. Morozov, V.I. Zhurba, O.V. Mats, V.N. Voyevodin
NSC-Kharkov Institute of Physics and Technology, 61108, Kharkov, Ukraine
E-mail: morozov@kipt.kharkov.ua

Helium thermal desorption spectra were investigated on the samples of type EK-181 (Fe12Cr2WVTaB) pre-implanted with 24 keV helium ions at current density 5 μA/cm2 in the dose range from 5 × 1016 to 4 × 1018 He/cm2 at the sample temperature Tirr ~ 295 K (RT).
In the spectrum of helium thermodesorption (TD) from the samples exposed to doses 5 × 1016 He/cm2 represents the temperature-scale smeared region of helium desorption with maxima in the temperature ~1470 K.
The increase in a dose of the implanted helium is accompanied by advancement of a spectrum of allocation of helium in a direction of fall of temperature. For a dose 4×1016 Не/см2 the spectrum helium TD represents to the area washed away on a temperature scale desorption with badly divided peaks in a range of temperatures 1000 – 1400 K.
At the further increase in a dose of the implanted helium there is a qualitative change of a spectrum TD the helium, shown in formation of peak to maximum temperature at Tm ~ 1050 K. The further increase in a dose of the implanted helium leads to growth of intensity of this peak of a spectrum TD and it becomes prevailing.
At doses above 1×1018 He/cm2 is formed low temperature region helium desorption in a kind washed away on a temperature scale of desorption region with a maximum at Tm ~ 400 K.
Proceeding from representation that atoms of helium in a crystal lattice of a steel form vacancy–helium complexes (Vn-Hem), peaks in a range of temperatures 1000 – 1400 K. 
The peak with temperature of a maximum ~1000 K testifies to formation ordered helium complexes with set parity Hen-Vm. At end of formation of these complexes ordered helium-vacancy it is formed low temperature area desorption helium in a kind washed away on a temperature scale of area десорбции with a maximum at Tm ~ 450 K.
The exit of a curve of quantity of kept helium in steel on saturation is observed after formation low temperature areas desorption helium.