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Recently, Ti–Ta-based metallic glass surface alloys (MGSAs) with attractive surface properties were successfully synthesized on TiNi substrates by additive pulsed melting of film/substrate systems. However, undesirable nanobubbles are often formed in the amorphous matrix. In this work, to reveal bubble characteristics and clarify the origin of its formation, the ∼1.5-μm thick Ti–Ta–Si–Ni MGSA was synthesized by 10-fold alternating of magnetron co-deposition of Ti60Ta30Si10 thin (100 nm) film and its pulsed e-beam (∼2.5 μs, ∼15 keV, 1.7 J/cm2) melting with a TiNi substrate. Transmission electron microscopy was utilized for quantitative analysis of bubbles. It has been shown that the Ar trapped during film deposition is the majority gas inside the bubbles. The Ar pressure inside the bubbles with mean diameter in range of ∼9 ÷ 16 nm predicted from the equation of state for Ar at 300 K varies in depth from ∼100 to 50 MPa. Experimental results and estimates of diffusion of Ar atoms in the surface melt indicate that nucleation and growth of bubbles occur in the Ar supersaturated liquid phase at the solidification/glass transition front. A high bubble-forming ability of Ti–Ta–Si–Ni system is consistent with the facts that Si addition decreases the melt surface tension and increases the Ar diffusivity due to eutectic reactions.

Irradiation of TiNi shape memory alloys with a microsecond low-energy (10–30 keV), high-current (10–25 kA) electron beam in surface melting modes induces microcrater formation, which limits the practical use of this method of surface modification. Potential centers of crater formation are inclusions, which are inherent to TiNi alloys. However, there is limited information about their role in crater formation and the nature of this phenomenon as applied to TiNi alloys. In this paper, the microstructural identification of inclusions was carried out in commercial (VIM) and precision TiNi alloys using TEM/SAED/EDS methods. The topographical features of microcraters formed by a single-pulse irradiation of TiNi samples near the surface melting threshold of the B2 matrix phase were identified. It was found by SEM/EDS-analysis, that microcraters are mainly nucleated on titanium oxycarbide TiC(O) (commercial alloy) and oxide Ti 4 Ni 2 O (precision alloy) inclusions; in both cases, the central region of microcraters is enriched with oxygen. The role of gradient capillary forces in the melt mass transfer (Marangoni effect), which determine the formation of microcraters, was analyzed. It was shown that thermocapillary forces play an insignificant role, while chemicapillary forces induced by decreasing a surface tension of the melt due to its oxygen enrichment can be sufficiently large to produce microcraters.

An important factor limiting the wide application of thin-film metallic glass (TFMG) coatings for improving the surface-sensitive properties of structural alloys is the poor adhesion of TFMG to substrates. This problem can be overcome through the synthesis of MG surface alloys (MGSAs) by additive pulsed electron-beam melting of film/substrate systems of high glass-forming ability. In this work, this approach is applied to the [film (Ti60Ta30Si10, at.%, 100 nm)/substrate (TiNi alloy)] system using a low-energy, high-current electron beam (~2.5 μs, ~15 keV, 1.7 J/cm2) at 10 synthesis cycles and 10 pulses per cycle. Using SEM/WDS, XRD and cross-sectional HRTEM/EDS/SAED analyses it has been found that ~1.5 μm thick SA has completely MG structure, in which the near-surface ~500 nm thick Ni-depleted layer has composition ~Ti56Ta23Ni11Si10. Beneath the MGSA, the ~200 nm thick nanocomposite Ti50Ni30÷40(Ta + Si)20÷10 sublayer, consisting of Ti2Ni nanograins embedded in the amorphous phase is formed. The nanocomposite sublayer is followed by the intermediate sublayer with the eutectic columnar nano-grain B2-structure, which provides the diffusion bonding of MGSA with unmelted TiNi substrate. The monotonic depth dependences of hardness, elastic modulus, depth recovery ratio and plasticity, obtained by indentation, indicate the mechanical compatibility of the MGSA and underlying sublayers with the TiNi substrate. The adhesion-related failure of the MGSA during scratch testing proceeds in the ductile mode mainly through the plastic flow of intermediate sublayer. Evaluation of shape memory effect and superelasticity by torsional deformation technique has shown that synthesis of the MGSA results in an almost 2-fold increase in the martensitic shear stress and significant decrease in the stress hysteresis width compared with the untreated TiNi samples. The irreversible residual strain is ~0.8% at a maximum strain of 6%. Potentiodynamic polarization measurements have shown that synthesis of the MGSA results in the significant enhancement in corrosion resistance of test samples in the Lock-Ringer salt solution.

An important factor limiting the wide application of magnetron-sputtered amorphous or nanocomposite thin-film coatings for improving surface-sensitive properties of structural alloys is the poor adhesion of coating to substrate. This problem can be overcome through the synthesis of surface alloys (SAs) by additive pulsed electron-beam melting of film/substrate systems of high glass-forming ability (GFA). In this work, this approach is applied to the “film (Ti85/70Nb15/30, at.%), 100 nm/substrate (TiNi SMA)” system using low-energy, high-current electron beam (~2.5 μs, ~15 keV, 1.7 J/cm2) at 10 synthesis cycles and 10 pulses per cycle. The melting/solidification conditions were evaluated using numerical modeling of pulsed heating, taking into account the formation of eutectic in the Ti-Ni-Nb system and initial temperature risen up to 473 K to the end of the synthesis. Using surface SEM/EDS, AES, XRD and cross-sectional HRTEM/EDS/SAED analyses it has been found that both SAs of thickness ~1.5–2 μm have depth-graded structure, in which outer Ni-depleted layer is the multiphase nanocomposite with quasicrystals followed by predominantly Ti-Ni-based amorphous sublayer. Beneath, the ~1 μm thick intermediate sublayer with eutectic columnar structures (B2 + Ti2Ni and B2 + Ti3Ni4 for first and second SA, correspondently), monotonic Nb substitution for Ni and diffusion transition to TiNi substrate is formed. Depth-graded structure of modified surface layers provides monotonic changes with depth in nanohardness, elastic modulus, depth recovery ratio and plasticity to the values of the TiNi substrate. For both SAs the evolution of structure in depth is in a reasonable agreement with glass forming composition range evaluated for Ti-Ni-Nb system using Miedema's model.

The regularities of surface cratering in commercial and precision TiNi alloys irradiated with a low-energy, high-current electron beam (LEHCEB) in dependence on non-metallic (TiC(O)) or intermetallic (Ti2Ni) inclusions presented in TiNi matrix are studied. The melting threshold of TiNi alloy was found to be achieved in the range of LEHCEBs energy density E s corresponding to 1.3-1.5 J/cm 2 . The dominant role of non-metallic inclusions [mainly, TiC(O)] in the nucleation of microcraters was found. The processes initiated by pulsed heating/melting near the inclusion/matrix interface were analyzed. It is proposed that the most important factor enabling the liquid-phase dissolution of inclusions and delivery of impurities of C and O [from TiC(O)] and O (from Ti 4 Ni 2 O x ) into TiNi melt are eutectic reactions taking place in the Ti-Ni-C and Ti-Ni-O systems near Ti 50 Ni 50 composition.

The paper presents a review of some new results of investigations on surface treatment of materials with pulsed (2–3 μs) low-energy (up to 10–40 keV), high-current (up to 30 kA, 1–40 J/cm 2 ) electron beams (LEHCEB). Effect of pulsed melting on chemical and phase composition of the near-surface layers of a pre-quenched high-speed steel (HSS) as well as the wear resistance of cutting tools made of the HSS have been studied. The microstructural evolution and phase transformations occurring in the surface layers of hard alloys (WC–Co, WC-30% Hadfield's steel), the surface hardening and the wear behavior are considered. Depth profiles of the elements in the surface alloys formed by pulsed melting of film-substrate systems are given. A new promising method for surface modification of dental alloys based on LEHCEB treatment is presented.

The surface morphology, chemical composition and microstructural evolution of the near-surface (up to 0.5 μm) layers of austenitic stainless steels (SS) 304L and 316L irradiated with a pulsed (2.5 μs) low-energy (20–30 keV), high-current (up to 30 kA) electron beam (2–10 J/cm 2 ) have been studied. It was revealed that the cratering on irradiation caused by the local overheating followed by explosive ejection of the material at the sites of localization of low-melting-point second-phase (e.g. FeS 2 ) particles having a low-thermal-conductivity occurs. The plate rolling stock SS 304L cratered far less than the rod stock one. Multiply repeated pulsed melting of SS 304L (plate) and 316L (rod) almost completely suppresses cratering and reduces the surface roughness compared to the untreated surface. Surface smoothing is accompanied by cleaning of the near-surface (≈50 nm) layer from O, C and N. As a result of fast (∼10 9 K/s) quenching from the melt, in the near-surface (≈0.5 μm) layer, a single-phase ( γ ) microstructure is formed with a grain size of 0.2–0.6 μm, which is almost two orders of magnitude lower compared to the untreated SS. The formation of such substructure allows to considerably enhance the electric strength of vacuum insulation and corrosion resistance of SS.

Monolithic TiN coatings deposited onto cemented carbide cutting tool inserts coated by PVD methods have been subjected to pulsed intense electron beam treatments in the energy range 3–5 J cm −2 . The temperature profiles for this rapid thermal process (RTP) covered the range between fusion of the cobalt binder in the carbide to surface fusion of the TiN coatings. The treatment caused extensive cracking and removed the atomic level defects, vacancies and dislocations, and residual stress. There was some nitrogen loss very close to the surface but no change in the stoichiometry of the bulk of the nitride. No changes were found in the microstructure of the carbide substrate below the coatings. Steel-turning tests showed that treatment of the coatings at the lowest power used, 3 J cm −2 , reduced the flank wear by a factor of about two.

Some experimental results are presented, related to practical applications of a holographic nondestructive technique for inspection of museum item conditions, especially in the detection of deformation, stress concentration and defect localization. These results are obtained using the basic principles of traditional double-exposure holographic interferometry, as well as its electronic variant with computer image processing. In the latter case the accuracy in displacement measurements was studied on a test object. Two museum items have been selected for their condition inspection: a XVIIIth century icon on wooden panel and a precolumbian terracotta anthropomorphic. The technique described can give quite accurate metrological information, and is also rather promising for rapid qualitative analysis of the object condition before and after restoration, as well as during its storage.

Possible applications of holography for cultural heritage study, demonstration and restoration, particularly in practical museum applications, are discussed. In this respect two main applications of holography are of interest: display holography and technical holography. The latter includes holographic NDT methods, three-dimensional measurements of objects, memory systems, and so on.

Plastic pipes dominated the low pressure gas distribution piping market during the last decade. Research on steel pipes has long since indicated that the susceptibility to rapid crack propagation (RCP) increases with increasing diameter. Although most plastic pipes used in gas distribution systems are of small diameter (

The characteristics of the radiation diffracted by dynamic gratings recorded in the frequency-degenerate forward four-beam mixing in sodium vapour are investigated. The maximum gain value was 300 for signal beam and 80 for the fourth arising beam with an input signal-to-pump beam intensity ratio of ≈3 × 10 -4

Volume phase hologram recording in pure LiNbO 3 crystals with applied electric field E ≈ 5 kV/cm is accompanied by considerable intensity redistribution of the writing beams by transient energy transfer. Practically the whole intensity of the donor beam may be transferred into the weak acceptor beam with initial intensity 3% from total incident intensity. This effect originates from transient phase mismatch of the recorded phase grating and fringe pattern in the applied electric field when the interacting beams have different intensities.

A speckle holography technique is discussed for measuring small displacements of objects. It is based on the sensitivity of the diffracted light intensity from a mutual shift between the hologram and the reconstructed speckle wave. The proposed method allows the measurement of both an object's lateral and longitudinal displacement without changing the arrangement of the apparatus. This set-up allows continuous measurements to be taken.

Possible applications of dynamic holograms for image amplification and image processing are discussed. The principal physical processes of holographic amplification of coherent light are analysed. Amplification of grey scale images during recording of dynamic holograms in pure reduced and Fe-doped crystals of LiNbO 3 is demonstrated. One-exposure technique of image subtraction or addition is proposed and realised in Fe-doped crystals of LiNbO 3 .