Phase analysis of explosive welded Ti-Cr/Ni steel in AS-received state and after heat treatment using synchrotron

Surface coatings protection is one of the most important processes ensuring efficient and economic use of basic materials, mostly of lower-quality. At interface of clad and basic material intermetallic phases are formed, representing quite different matrix with dissimilar properties unlike the welded materials. One type of surface coating is explosive bonding which belongs to group of pressure welding. The work is focused on interface shape line, inhomogeneities in vicinity of the wave joint both in basic material and in vicinity of weld line of the Ti and Cr/Ni stainless steel (SS) matrix. Investigated weld was both in as-received state and after heat treatment carried out at 600 C/90 minutes/air. Presented phases have been identified using X-ray diffraction performed by synchrotron. The Ti , Fe-fcc, Fe-bcc and intermetallic phases Fe2Ti were detected at interface area.Web of Science5941614161

Structure and mechanical properties of explosive welded Mg/Al bimetal

In the article we analyzed shape, local mechanical properties, chemical and phase composition of Magnesium/Aluminium cladded material prepared by explosion welding. In particular we focus our investigation on Mg/Al interface and areas close to the joint. Hardness of the joined materials measured far from their interface is similar for both materials, however in the region of interface the hardness drops down by 40%. Phase transformations in the interface was examined by a hard X-ray micro-diffraction experiment performed at beamline P07 at PETRA III at the energy of 99 keV which helped us identify in Al: fcc-Al, Al2Cu tetragonal and Al7Cu2Fe tetragonal and in Mg: hcp-Mg, Mg2Si cubic phases. In the interface we haven’t observed any new intermetallics, but computation of lattice parameters and profiles of Al and Mg peaks proved an existence of solid solution with different gradient of chemical composition.Web of Science5941597159

Influence of Hot Plastic Deformation in γ and (γ + α) Area on the Structure and Mechanical Properties of High-Strength Low-Alloy (HSLA) Steel

The main goal of this study was to develop a new processing technology for a high-strength low-alloy (HSLA) steel in order to maximize the mechanical properties attainable at its low alloy levels. Samples of the steel were processed using thermal deformation schedules carried out in single-phase (γ) and dual-phase (γ + α) regions. The samples were rolled at unconventional finishing temperatures, their final mechanical properties were measured, and their strength and plasticity behavior was analyzed. The resulting microstructures were observed using optical and transmission electron microscopy (TEM). They consisted of martensite, ferrite and (NbV)CN precipitates. The study also explored the process of ferrite formation and its influence on the mechanical properties of the material

Preparation of dispersion strengthened nanocomposite with Al2O3 and MgO particles by spark plasma sintering

Nanocomposites are multiphase materials in which at least one of the structural compounds has a size below 100 nm. The subject of this work is creation of a dispersion-strengthened nanocomposite (DSC) with copper matrix. There are many dispersions that are possible to be used in DSC with copper matrix, such as Al2O3, Y3O2, TiO2, and WC. In this work we used Al2O3 due to the possibility of making even dispersion in the material and its economical availability. Such composites exhibit thermal stability of their mechanical properties up to 900 °C for at least 1 hour exposure, which opens new possibilities for use of such materials in high-temperature, high-strength applications. Materials created by our team exhibited good mechanical properties, namely hardness, which was up to 136 HB; however, it has to be noted that amount of dispersion particles had a direct effect on the hardness of the composite. Properties of the DSC´s are also dependent on the method of its preparation and compactization. Composites in this work were prepared by powder metallurgy method and sintered by spark plasma sintering, which allowed these composites to reach 99% density. Furthermore, DSCs were tested for their thermal stability, and their properties were evaluated and compared even with precipitation-strengthened copper-chrome material in order to show potential of possible usage of DSCs in spot welding applications, which require high strength, hardness, and electric conductivity

Influence of Hot Plastic Deformation in γ and (γ + α) Area on the Structure and Mechanical Properties of High-Strength Low-Alloy (HSLA) Steel

The main goal of this study was to develop a new processing technology for a high-strength low-alloy (HSLA) steel in order to maximize the mechanical properties attainable at its low alloy levels. Samples of the steel were processed using thermal deformation schedules carried out in single-phase (γ) and dual-phase (γ + α) regions. The samples were rolled at unconventional finishing temperatures, their final mechanical properties were measured, and their strength and plasticity behavior was analyzed. The resulting microstructures were observed using optical and transmission electron microscopy (TEM). They consisted of martensite, ferrite and (NbV)CN precipitates. The study also explored the process of ferrite formation and its influence on the mechanical properties of the material

Influence of Nanoparticle Size on Strain at the Core-Shell Interface

This work deals with the strain at the core-shell interface of Fe nanoparticles. Series of Fe nanoparticles with various mean diameters were prepared by precipitation in solid state in binary Cu-Fe alloy. Further, nanoparticles were isolated by dissolution of Cu matrix. High-energy X-ray diffraction (XRD) was used to probe structure of nanoparticles. XRD measurements suggest presence of the core-shell structure, where core and shell of the nanoparticles are formed of α-Fe and CuFe$_{2}$O$_{4}$ phase, respectively. Strains in core and shell were estimated as a function of nanoparticles size by Williamson-Hall method

Structure Characterisation of Electrodeposited Ni-Co Alloy

This paper is focused to structure characterization of two differently electrodeposited Ni-Co alloys on the copper surface. The chemical composition of the layers was determined by the EDX analysis in the scanning electron microscope. Phase analysis was realized by diffraction in the transmission mode using synchrotron radiation. Diffraction patterns also show the preferred orientation in the coating with saccharine addition

Hydrogen Embrittlement Behavior of Plastically Pre-Strained and Cathodically Hydrogen-Charged 316H Grade Austenitic Stainless Steel

In this work, the effects of electrochemical hydrogen charging of 316H grade austenitic stainless steel were investigated in order to characterize its hydrogen embrittlement (HE) resistance. The as-received 316H material was in a fully recrystallized (solution-annealed) material condition. The susceptibility to HE of the studied material was evaluated by determination of the embrittlement index from the results of conventional uniaxial tensile tests of nonhydrogenated and hydrogen-charged test specimens. The study was focused on the effects of two selected plastic pre-strain levels of tensile specimens on their resulting HE resistance. The selected pre-strains corresponded to the tensile stress conditions within the “yield stress–ultimate tensile strength” (YS–UTS) range and directly at the UTS point. The obtained embrittlement indices for the presently used pre-straining and hydrogen charging conditions indicated that the HE of the studied material states was small. However, it was revealed that the observed degradation of deformation properties of plastically pre-strained and hydrogen-charged materials was mainly caused by gradual plasticity exhaustion due to tensile straining, which well correlated with the observed effects indicated by electron backscatter diffraction analyses and indentation hardness measurements

Microstructure Changes and Improvement in the Mechanical Properties of As-Cast AlSi7MgCu0.5AlSi_{7}MgCu_{0.5} Alloy Induced by the Heat Treatment and ECAP Technique at Room Temperature

The changes in the microstructure and improvement in the mechanical properties of as-cast AlSi7MgCu0.5 alloy induced by the heat treatment and technique of equal channel angular pressing (ECAP) were investigated. The heat treatment of as-cast alloy performed before the ECAP technique was required to increase the plasticity of the alloy. Therefore, the samples of analysed alloys were solution annealed at optimized temperature of 823 K for 4 hours to dissolve the particles of intermetallic $π(Al_{8}FeMg_{3}Si_{6})$ phase and to spheroidize the Si particles. Subsequently, water quenching and artificial ageing at optimized temperature of 573 K for 5 hours was used to obtain an overaged alloy state. The microstructure of alloy was consisted of α(Al) solid solution, eutectic Si particles, and intermetallic $β(Mg_{2}Si)$, $Q-Al_{4}Mg_{5}Si_{4}Cu, α-Al_{12}(Fe,Mn)_{3}Si$, and/or $α-Al_{15}(Fe,Mn)_{3}Si_{2}$ phase particles. The crystal structure of present phases was confirmed by hard X-ray diffraction at Deutsches Elektronen-Synchrotron (DESY) in Hamburg and by the selected area electron diffraction (SAED) performed inside the transmission electron microscope (TEM). The heat-treated alloy was processed by ECAP at room temperature following route A. Repetitive ECAP of alloy homogenized the heterogeneous as-cast microstructure and formed the ultrafine subgrain microstructure with elongated subgrains of 0.2 µm in width and 0.65 µm in length and the high dislocation density. Microstructural changes in alloy induced by both heat treatment and ECAP led to the high strain hardening of the alloy that appeared in an improvement in strength, ductility, and microhardness of alloy in comparison with as-cast alloy state