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Mordyuk B.N.,NASU G.V. Kurdyumov Institute For Metal Physics | Iefimov M.O.,Frantzevich Institute for Problems of Materials Science | Grinkevych K.E.,Frantzevich Institute for Problems of Materials Science | Sameljuk A.V.,Frantzevich Institute for Problems of Materials Science | Danylenko M.I.,Frantzevich Institute for Problems of Materials Science
Surface and Coatings Technology | Year: 2011

Near-surface layers in aluminium specimens are modified using quasicrystalline (QC) AlCuFe particles introduced into a zone of severe plastic deformation induced by ultrasonic impact peening (UIP). Two types of QC particles are used: atomized with average size of approx. 25 μm (coarse QC-c-QC) and milled - 0.3-0.5 μm (fine QC-f-QC). The effect of QC particles of different sizes on microstructure and wear resistance of sub-surface composite layers in aluminium is studied in this paper. XRD, SEM and TEM studies of reinforced aluminium layers allow establishing the links between microstructural features of the layers and their sliding wear. The formed layers of composites reinforced with both types of QC particles demonstrate almost double increment in wear resistance when compared to that of annealed aluminium. It is due to the combination of several factors: (i) high hardness and high wear resistance of QC reinforcement (more efficient for c-QC); (ii) relatively strong interfacial bonding of homogeneously dispersed reinforcing QC particles; (iii) fine grain structure of the Al matrix (f-QC) or increased density of dislocations arranged in fine dislocation-cell structure (c-QC) - i.e. increased volume fraction of grain boundaries/dense dislocation walls. © 2011 Elsevier B.V. Source


Kindrachuk V.M.,BAM Federal Institute of Materials Research and Testing | Galanov B.A.,Frantzevich Institute for Problems of Materials Science
Journal of the Mechanics and Physics of Solids | Year: 2014

A computationally efficient solution scheme is presented for the mechanical problems whose formulations include the Kuhn-Tucker or Signorini-Fichera conditions. It is proposed to reformulate these problems replacing inequalities in these conditions by equations with respect to new unknowns. The solutions of the modified problems have simple physical meanings and determine uniquely the unknowns of the original problems. The approach avoids application of multi-valued operators (inclusions or inequalities) in formulation of the problems. Hence, the modified formulations are suitable for numerical analysis using established powerful mathematical methods and corresponding solvers developed for solving systems of non-linear equations. To demonstrate the advantages of the proposed approach, it is applied for solving problems in two different areas: constitutive modeling of single-crystal plasticity and mixed boundary value problems of elastic contact mechanics with free boundaries. The original formulations of these problems contain respectively the Kuhn-Tucker and Signorini-Fichera conditions. A problem of the former area is integrated using an implicit integration scheme based on the return-mapping algorithm. The derived integration scheme is free of any update procedure for identification of active slip systems. A problem of the latter area is reduced to solution of non-linear integral boundary equations (NBIEs). Numerical examples demonstrate stability and efficiency of the solution procedures and reflect the mathematical similarities between the both non-linear problems. © 2013 Elsevier Ltd. Source


Mordyuk B.N.,NASU G.V. Kurdyumov Institute For Metal Physics | Silberschmidt V.V.,Loughborough University | Prokopenko G.I.,NASU G.V. Kurdyumov Institute For Metal Physics | Nesterenko Y.V.,Kharkiv Polytechnic Institute | Iefimov M.O.,Frantzevich Institute for Problems of Materials Science
Materials Characterization | Year: 2010

Two types of Ti particles are used in an ultrasonic impact peening (UIP) process to modify sub-surface layers of cp aluminium atomized, with an average size of approx. 20 μm and milled (0.3-0.5 μm). They are introduced into a zone of severe plastic deformation induced by UIP. The effect of Ti particles of different sizes on microstructure, phase composition, microhardness and wear resistance of sub-surface composite layers in aluminium is studied in this paper. The formed layers of a composite reinforced with smaller particles have a highly misoriented fine-grain microstructure of its matrix with a mean grain size of 200-400 nm, while reinforcement with larger particles results in relatively large Al grains (1-2 μm). XRD, SEM, EDX and TEM studies confirm significantly higher particle/matrix bonding in the former case due to formation of a Ti3Al interlayer around Ti particles with rough surface caused by milling. Different microstructures determine hardness and wear resistance of reinforced aluminium layers: while higher magnitudes of microhardness are observed for both composites (when compared with those of annealed and UIP-treated aluminium), the wear resistance is improved only in the case of reinforcement with small particles. © 2010 Elsevier Inc. Source


Mordyuk B.N.,NASU G.V. Kurdyumov Institute For Metal Physics | Prokopenko G.I.,NASU G.V. Kurdyumov Institute For Metal Physics | Milman Y.,Frantzevich Institute for Problems of Materials Science | Iefimov M.O.,Frantzevich Institute for Problems of Materials Science | And 3 more authors.
Wear | Year: 2014

Aluminium alloys reinforced with ceramic, intermetallic or quasicrystalline particles can fill the needs of automotive and aerospace industries due to their superior properties. In this paper, near-surface layers in Al-6Mg alloy specimens were modified using an ultrasonic impact treatment (UIT) process, which induces mechanical mixing of matrix and reinforces quasicrystalline (QC) Al63Cu25Fe12 particles to be introduced into a zone of severe plastic deformation. The wear and friction behaviours of the matrix alloy and QC reinforced layers were investigated in quasi-static and dynamic conditions with particular attention to the effects of QC particles size and test type on wear resistance and microhardness of sub-surface composite layers in Al-6Mg alloy. XRD and SEM analyses show that the layers of 40-50μm thickness are fabricated by the UIT process which contain homogeneously dispersed fine QCF (0.5-3μm) or coarse QCC (~15μm) particles, with volume fractions Vf of about 9% and 22%, respectively. In comparison to the annealed Al-6Mg alloy, noticeable increment in wear resistance was registered only for the composite layer reinforced with QCF particles. On the contrary, the QCC particles being fractured at the fabrication process and/or at the wear tests facilitate three-body abrasive wear conditions and deteriorate the wear resistance of the alloy. SEM and confocal laser microscopy show changes in wear mechanism from microcutting/ploughing in the QCF reinforced layer to microcracking/fracturing in the case of QCC reinforcement. Fine QCF particles are preferred for better wear resistance both at the quasi-static and dynamic conditions. © 2014 Elsevier B.V. Source


Mordyuk B.N.,NASU G.V. Kurdyumov Institute For Metal Physics | Prokopenko G.I.,NASU G.V. Kurdyumov Institute For Metal Physics | Milman Y.,Frantzevich Institute for Problems of Materials Science | Iefimov M.O.,Frantzevich Institute for Problems of Materials Science | Sameljuk A.V.,Frantzevich Institute for Problems of Materials Science
Materials Science and Engineering A | Year: 2013

Composite layer reinforced with quasicrystalline (QC) Al63Cu25Fe12 particles was fabricated on the surface of Al-6Mg alloy specimens by ultrasonic impact peening (UIP). Stress-controlled fatigue response of the specimens was studied and compared with those for the annealed and UIP-treated specimens. The notch effect of the UIP induced surface roughness calculated in terms of the stress concentration factor does not exceed~10%. XRD, OM and SEM analyses were used to characterize formed surface layers and fatigue fracture surfaces. Surface composite layer of 40-50μm thick contains the homogeneously dispersed QC particles (the volume fraction Vf~0.15) trapped by high compressive residual stresses. The layer demonstrates almost triple increase in microhardness comparing to that for the annealed alloy and twice exceeding of that for the UIP-treated specimen. Superior fatigue endurance of Al-6Mg alloy after the UIP process and the UIP-induced formation of the composite layer is explained by sub-surface fatigue cracks' initiation promoted with high compressive residual stresses and tight interfacial bonding of QC reinforcement and the matrix alloy. The improved fatigue behavior of the UIP-treated specimens in both the low cycle and high cycle regimes can be ensured by combination of the following favorable characteristics: (i) sufficiently high ductility and resistance to fatigue damage and crack growth in the core parent material along with (ii) superior fatigue strength supported by high microhardness and compressive stresses in the surface layer, which contains fine grained matrix and/or uniformly distributed and tightly bonded QC reinforcements. © 2012 Elsevier B.V. Source

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