Strengthening Mechanisms in the Surface Layer of Duralumin Modified by a High Current Pulsed Relativistic Electron Beam

Abstract

The mechanisms of strengthening of the surface layer of D16AT aluminum alloy irradiated with a high-current relativistic electron beam were studied. The alloy was irradiated with an electron beam with a particle energy of 0.35 MeV, a beam current of 2.0 kA, and a pulse duration of 5 μs. This article shows that the processing of D16AT aluminum alloy by a high-current relativistic electron beam leads to melting of irradiated surface and the formation of a surface layer with a modified structural-phase state. The thickness of this layer is approximately 100 m. A solid solution based on aluminum is the main constituent of this layer. At the same time, intermetallic phases that were present in the initial state of the alloy cannot be detected by means of X-ray diffractometry. It was established that processing of the surface of D16AT alloy with a pulsed electron beam leads to grain refining. In the initial state of the alloy, the average grain size is 11 m. In the modified layer, the average grain size is approximately 0.8 m. The microhardness of the irradiated layer increases by almost 50 %. The contribution of different strengthening mechanisms to the change of strength characteristics of the modified surface layer was analyzed. It was shown that the dispersion mechanism makes the main contribution to the strengthening of the alloy in the initial state. While the dislocation mechanism of strengthening plays a key role in increasing the microhardness of the irradiated layer. The importance of these observations for thermomechanical processing of aluminum alloys in order to further improve their strength characteristics was discussed.

Optical Parameters of Aluminum Alloy Samples Irradiated by High Current Relativistic Electron Beams

“…SAMPLES STUDIED This work deals with the samples made from the D16AT aluminum alloy obtained during the wide investigations performed to study a modification of the surface of a metal target by the high current pulsed relativistic electron beams. Details of the preparation, processing, and postprocessing of the samples are presented in the works [13], [14], and [15]. Generally, the interaction of the beams with metal targets represents a rather complex sequence of processes, initiated by radiation and ionization energy losses of particles.…”

“…This leads to a change in the essential operational properties of the surface layer of irradiated samples, such as plasticity, corrosion and erosion resistance, hardness, etc. Exposure to the electron impact results in the refinement of the grain structure down to nanoscale sizes [14], the redistribution of elements at grain boundaries [15], etc. Figure 2 shows the changes in the surface layer of the D16AT alloy sample due to the electron beam impact.…”