Перспективы получения наноструктур при действии импульсного лазерного излучения на стали

Abstract

На основе решения совместной задачи теплопроводности и термоупругости получены поля температур при действии импульсного лазерного излучения на стали 20, 40, 45, 40Х, У8, У12 с учетом критериев: требуемые температуры – 500...1500 К, необходимые скорости нарастания температур – более 10⁷ К/с. Определены технологические параметры лазерной обработки (плотность теплового потока, время его действия) для образования наноструктур.

We considered the problem of action the effects of ionizing radiation on materials. We solved the problem of heat conduction and joint thermo-elasticity. For a low-carbon and high-carbon steels obtained temperature fields in the case of pulsed exposure to ionizing radiation. Estimated rate of rise of temperature. As a criterion f or the formation of nanostructures were taken as follows: – The presence of heat in the formation of nanostructures (500–1500 K); – Ensuring the growth rate of temperature higher than 10⁷ K/s; – Small dimensions, in which the temperature exceeds the allowable 1500 for no more than 2 times 10⁻⁷ sec. with (a slight increase in grain as a result of high temperatures, but not sufficient to reach the values of phase transformations). For steels 20, 40, 45, 40X, U8 and U12 are obtained depending on the maximum temperature in the spot at a depth of 1 micron, depending on the time, which made it possible to find a treatment method: heat flux density and time of the action in which is possible to obtain nanostructures for all the studied materials. The examples of construction of spatio-temporal patterns of temperature fields that allow you to estimate the size of the zone where possible to obtain nanostructures by heat flux densities from 10¹⁰ to 3 ∙ 10¹⁰ W/m² an running times with 3 ∙ 10⁻⁷. It is shown that reducing the heat flux to 10⁸ – 3 ∙ 10⁸ W/m² an time of action with 3 ∙ 10⁻³ sec. Can achieve substantially the same temperatures, but in this case, as shownin the experimental work Antropova can produce micro (1.3 – 2 microns) submicron structures (0.7–0.9 microns), which is associated with the fact that the growth rate of temperature is of the ≈ 10⁶ K/s, which does not allow its value to more than 10⁷ K/s, which once again confirms the thesis of the need to meet these criteria. In work zones nanostructures based heat flux on the time of its action, where there are restrictions on the maximum and minimum temperature, the rate of temperature rise and the possible destruction of the thermoelastic stresses. All this allows you to find the technological parameters of pulsed laser radiation; heat flux and its duration when ensure the production of nanostructured layers.