High-intensity Pulsed Electron Beam Research Articles

Fractography of Fatigue Fracture Surface in Silumin Subjected to Electron-Beam Processing

The surface modification of the eutectic silumin with high-intensity pulsed electron beam has been carried out. Multi-cycle fatigue tests were performed and irradiation mode made possible the increase in the silumin fatigue life more than 3.5 times was determined. Studies of the structure of the surface irradiation and surface fatigue fracture of silumin in the initial (unirradiated) state and after modification with intense pulsed electron beam were carried out by methods of scanning electron microscopy. It has been shown, that in mode of partial melting of the irradiation surface the modification process of silicon plates is accompanied by the formation of numerous large micropores along the boundary plate/matrix and microcracks located in the silicon plates. A multi-modal structure (grain size within 30-50 μm with silicon particles up to 10 μm located on the boundaries) is formed in stable melting mode, as well as subgrain structure in the form of crystallization cells from 100 to 250 μm in size). Formation of a multi-modal, multi-phase, submicro- and nanosize structure assisting to a significant increase in the critical length of the crack, the safety coefficient and decrease in step of cracks for loading cycle was the main cause for the increase in silumin fatigue life.

Modification of the titanium film–aluminum substrate system by a high-intensity pulsed electron beam with a submillisecond duration

Numerical simulation of the thermal processes that occur during doping of an Al surface with titanium by the method of liquid-phase mixing of a film–substrate system using an intense pulsed electron beam is carried out. As a result of our studies, it is shown that melting of the Ti-film–Al-substrate system makes it possible to form a multiphase submicrocrystalline structure with high strength and tribological properties in the surface layer.

Modification of the sample's surface of hypereutectic silumin by pulsed electron beam

The article presents the results of the analysis of the elemental and phase composition, defect substructures. It demonstrates strength and tribological characteristics of the aluminium-silicon alloy of the hypereutectic composition in the cast state and after irradiation with a high-intensity pulsed electron beam of a submillisecond exposure duration (a Solo installation, Institute of High Current Electrons of the Siberian Branch of the Russian Academy of Sciences). The research has been conducted using optical and scanning electron microscopy, and the X-ray phase analysis. Mechanical properties have been characterized by microhardness, tribological properties - by wear resistance and the friction coefficient value. Irradiation of silumin with the high-intensity pulsed electron beam has led to the modification of the surface layer up to 1000 microns thick. The surface layer with the thickness of up to 100 microns is characterized by melting of all phases present in the alloy; subsequent highspeed crystallization leads to the formation of a submicro- and nanocrystalline structure in this layer. The hardness of the modified layer decreases with the increasing distance from the surface exposure. The hardness of the surface layer is more than twice the hardness of cast silumin. Durability of silumin treated with a high intensity electron beam is ≈ 1, 2 times as much as the wear resistance of the cast material.

The increase in eutectic silumin fatigue life caused by electron beam processing

Eutectic silumin was processed with a high-intensity pulsed electron beam, and a multi-fold increase in the material fatigue life was discovered. Scanning electron microscopy was used to study the modified layer structure and the fracture surface of silumin subjected to high-cycle fatigue breakdown tests. The factors responsible for the increase in fatigue life of silumin were identified and analyzed.

FORMATION OF SURFACE ALLOYS AT MELTING OF FILM-SUBSTRATE SYSTEM BY HIGH-INTENSITY PULSED ELECTRON BEAM. REPORT 1

Abstract. The paper examines the results of the comparative analysis of the elemental and phase composition, defective substructure of a surface layer of 40Cr steel, subjected, fi rstly, to the irradiation with highintensity pulsed electron beam and, secondly, to the alloying by means of melting of fi lm (Cu) – substrate (40Cr steel) system, when irradiating with high-intensity pulsed electron beam. Evolution regularities of the structure of steel surface layer have been revealed in dependence on electron beam energy density. It has been shown that high-speed crystallization and the subsequent hardening of 40Cr steel leads to the formation of the modifi ed layer with the thickness up to 30 μm. The formation of cell structure in a surface layer has been revealed, average cell sizes increase from 240 nm to 500 nm at the growth of electron beam energy density from 10 J/cm2 to 20 J/cm2 (N = 10 imp.). The irradiation with high-intensity pulsed electron beam of fi lm (Cu) – substrate (40Cr steel) system is accompanied by the formation of a surface alloy with a hardening structure, hardened with nanodimensional copper particle extractions.

Structure-phase states of silumin surface layer after electron beam and high cycle fatigue

Modification of eutectic silumin surface has been implemented by high-intensity pulsed electron beam. The irradiation mode has been revealed; it allows increasing silumin fatigue life in more than 3.5 times. It has been established that the main reason of this fact is the formation of a multiphase submicro- and nanosized structure. It has been elicited that the most danger stress concentrators are large silicon plates situated on the surface and near-surface layers.

Structure of the surface layer of a wear-resistant coating after treatment with a high-intensity electron beam

Transmission electron microscopy is used to investigate the carbon extraction replicas of a wearresistant surface layer formed on Hardox 400 steel and its phase composition. The formation of a multiphase state is revealed, which includes a-iron grains and inclusions of carbide phases based on iron, chromium, and niobium. The surface layer is additionally treated by a high-intensity pulsed electron beam. The relative position of α-iron grains and particles of carbide phases is examined by the electron-diffraction microscopy of thin foils. The main carbide phase is iron carbide located as extended interlayers which separate a-iron grains. Nanoscale particles of chromium and niobium carbides are located at the interfaces of the a-iron–iron-carbide system and in the body of the a-iron grains. It is established that the surface layer is in the elastic-stress state during pulsed electron-beam treatment due to ultrahigh heating and cooling rates. It is shown that stress concentrators are the interphase boundaries between the carbide and the a-phase of iron.

Fatigue life of silumin treated with a high-intensity pulsed electron beam

The regularities of the formation of the structure of silumin irradiated with a high-intensity electron beam in different modes are revealed using optical and scanning electron microscopy. The optimum irradiation mode that allows one to increase the fatigue life of this material by a factor of up to 3.5 is determined. The probable causes of the observed effect are investigated.

Structure of electroexplosive TiB2–Ni composite coatings after electron beam processing

High-intensity electron beam modification of electroexplosive TiB2–Ni composite coatings is conducted for the first time. The phase and elemental composition of the surface layer of steel Hardox 450 subjected to electroexplosive spraying (EES) of the TiB2–Ni composite coating and subsequent irradiation with a submillisecond high-intensity pulsed electron beam are studied. Electron beam processing (EBP) modes that provide the formation of dense glossy surface layers based on titanium diboride and nickel with a submicrocrystalline structure are revealed. It is shown that EBP of a layer subjected to EES conducted in a melting mode leads to the formation of a surface layer with homogeneous structure and concentration.

Fatigue life of silumin irradiated by high intensity pulsed electron beam

The electron-beam processing of silumin, leading to the evolution of structure-phase state of its surface is carried out. It has been shown that this alloy is a multiphase material and contains, except an aluminum-based phase, the particles of intermetallic compounds of Al-Si- Fe-Mn. It is shown that electron beam treatment of the eutectic silumin surface increases the fatigue service life more than in 3.5 times. The analysis of structure-phase states modification of silumin subjected to electron beam treatment with the following fatigue loading up to the failure is carried out by methods of optical and scanning electron diffraction microscopy. Analysis of the surface layer structure revealed the sources of nucleation of submicrocracks. It is revealed that the large silicon plates located on the surface and in the subsurface layer are the most dangerous stress concentrators.

Structure and Properties of a Coating (TiCuN) – Substrate (А7) System Modified with a High-Intenisty Electron Beam

The data obtained via an analysis of the structure and properties of a surface layer of technical grade aluminum (A7) modified by forming a thin TiCuN coating, followed by irradiation with a high-intensity submillisecond pulsed electron beam, are presented. The results of numerical modeling of the temperature fields and phase transformations in the surface layers of the coating (TiCuN)) and the substrate (А7), irradiated with a high-intensity pulsed electron beam, are also reported. The regimes of irradiation are identified, which ensure fusion of the coating into the substrate surface. An analysis of tribological properties (wear resistance and friction coefficient) of the TiCuN coating – А7substrate system is performed.

Modification of a Coating (Tin) – Substrate (Vt1-0) System with High-Intensity Pulsed Electron Beams

The data on numerical simulation of the temperature fields and phase transformations in a surface layer of a coating (TiN) – substrate (VT1-0) system irradiated with a high-intensity pulsed electron beam are reported. The operating conditions of beam irradiation are identified, which ensure fusion of the coating into the substrate surface. The investigations of structure and phase compositions of the coating and substrate are performed and their transformations revealed under conditions of electron-beam treatment indicate a good qualitative and quantitative agreement with the results of simulation of thermal processes.

STRUCTURAL-SCALE LEVELS OF FATIGUE DURABILITY INCREASE OF STEELS AND ALLOYS BY ELECTRON-BEAM TREATMENT

The electron-beam treatment of different classes of steels (Fe– 0.1C–18Cr–10Ni–1Ti, Fe–0.2C–23Cr–18Ni, Fe–0.2C–13Cr, Fe– 0.76C–1V) and silumin (Al – 12 % Si) with the parameters: electron beam energy density 10 – 40 J/cm2, pulse duration 50 – 150 μs, pulse number 3 – 5, frequency 0.3 Hz) leads to the increase of cycle numbers up to the fracture in ~ 3.5 times. The studies of structure-phase states and defect substructure of these materials were carried out using the methods of scanning and transmission electron diffraction microscopy. It was shown that the increase in fatigue life of steel is due to the transformation of the structure of the surface layer of the material occurring during irradiation of samples high-intensity pulsed electron beam. It was suggested that the physical sense of the impact of multi-level structure-phase state on the mechanical properties of the surface layer of the material is in the redistribution of elastic energy as due to the interaction of the elastic fields of structural elements of different scale levels, and by reducing the scale level of plastic strain localization.

Formation of Gradient Multiphase Nanostructured Surface Layers Using the Electron-Ion-Plasma Combined Method

The data of the study of the elemental and phase composition, the condition of the defect substructure, mechanical and tribological characteristics of titanium alloy VT6 subjected to electroexplosive carburization with a sample of titanium diboride powder and the subsequent treatment by high-intensity pulsed electron beam is presented. It has been established that the main mechanisms responsible for an increase in the mechanical and tribological properties of the material are solid, dispersion, and grain boundary.

Fractography of the fatigue fracture surface of silumin irradiated by high-intensity pulsed electron beam

Irradiation mode has been revealed allowing to increase the silumin fatigue service life in three times, it was established that this fact is caused by the formation of multi-modal, multi-phase, submicro - and nano-structure able to lead to a significant increase in the critical length of crack.

Formation of the surface alloys by high-intensity pulsed electron beam irradiation of the coating/substrate system

The results of the analysis of the structure and properties of the surface layer of aluminum A7 subjected to alloying by the intense pulsed electron beam melting of the film / substrate system. Fold increase in strength and tribological properties of the modified surface layer due to the formation of submicro - nanoscale multiphase structure have been revealed.

Transient high heat load tests on tungsten coating by high-intensity current pulsed electron beam

Three kinds of tungsten coatings are fabricated by means of APS and CVD, and evaluated by transient high heat load tests by 25 high-intensity current pulsed electron beam pulses with a duration of 0.2ms and power densities of 0.4, 0.6 and 0.8GW/m2. Remelting and solidification are found on post-test APS-W coating. However, cracks are developed for the same power densities for the CVD-W coating. APS-W coatings have about 20 times mass loss of CVD-W coating. The mass loss is related to the peak surface temperature of the APS-W coating exceeding the tungsten melting point (3410°C) during electron beam irradiation. The CVD-W coating during testing was only 1000°C.

Surface layer of commercially pure VT1-0 titanium after electric-explosion alloying and subsequent treatment by a high-intensity pulsed electron beam

The structure, phase composition, and mechanical, tribological, and corrosional properties of commercially pure VT1-0 titanium are investigated after electric-explosion alloying and subsequent treatment by a high-intensity pulsed electron beam. Treatment conditions that greatly increase the properties of the titanium are identified. The physical factors at work here are considered.

Modification of Structure and Properties of Titanium Surfaces During Formation of Silicides and Borides Initiated by High-Energy Treatment

An analysis of binary (Ti–Si, Ti–В, Si–B) and ternary (Ti–Si–B) phase states is made, their diagrams are presented, and a possibility for formation of a large number of metastable compounds is revealed. The latter are found to form as a result of application of non-equilibrium conditions in the course of material treatment with concentrated high-energy flows. Using an x-ray diffraction analysis and electron-diffraction microscopy, the phase composition of the surface layer of technical-grade titanium (VT1-0) treated by concentrated energy flows (irradiation with plasma from electrical wire explosion and high-intensity pulsed electron beam) is investigated.

Generation of high-intensity pulsed low-energy electron beams in a channel spark system

The generation of a high-intensity pulsed beam of low-energy (5–10 keV) electrons in a gun of the channel spark type is considered. It is experimentally established that intense preionization in the transport channel, in combination with a pulsed accelerating voltage applied to the cathode, ensures the generation of pulsed electron beams with a current buildup time above 1011 A/s, a current density above 10 kA/cm2, and an amplitude about 1.5–2 times the characteristic Alfven current.