Influence of Nanoparticles Reinforcements on Aluminium 6061 Alloys Fabricated via Novel Ultrasonic Aided Rheo-Squeeze Casting Method

This study emphasis on a novel fabrication technique to fabricate hybrid cermets using Al 6061 alloy with nano sized SiC, Al2O3 and TiO2 as reinforcements. During the fabrication process, the melted pool was ultrasonicated to disperse nanoparticles at 20 kHz for 5 min and pressure of 50 MPa was applied to eliminate voids. The influence of nanoparticles on physical, thermal and mechanical properties were evaluated by tensile, wear and thermal studies. Cermets with Al2O3 reinforcements showed higher mechanical performance compared to Al alloy. This enhancement could be related to the uniform distribution of Al2O3 with refinement in grain size of Al alloy which was observed via surface analysis. The morphological studies provided justifiable evidence of homogeneous distribution, nominal cluster along with agglomeration and cavities shrinking on the cermets. The agglomeration of nanoparticles along with SiC protected the cermet in corrosion and abrasive wear by ~ 97% and ~ 71%. The study evidenced the novel fabrication method using ultrasonic rheo-squeeze casting led to improvement in mechanical and thermal properties of the hybrid cermets. Graphical abstract

The study of the formation of nanocomposite thin-walled fluoroplastic coatings on metal substrates of various nature using atomic force microscopy

The paper presents the results of the research on the formation of nanocomposite fluoroplastic thin-wall coatings on substrates: 45 steel; copper and Al, formed under various conditions using the method of atomic force microscopy. Morphological features of the nanophase thin-layer fluoroplastic coatings with disperse nanoparticles have been studied. A model for the formation of nanophase composite systems is proposed.

Механизм влияния дисперсных наночастиц на параметры мартенситных переходов в сплавах с эффектом памяти формы

Within the diffuse martensitic transition theory based on the thermodynamic and kinetic equations and relations, the mechanism of influence of disperse nanoparticles on the parameters of martensitic transitions in alloys with the shape memory effect (SME) is analyzed. The objects of the analysis are the TiNi alloy with the varied sizes of Ti_3Ni_4 particle at their constant volume concentration, and the NiMnGaTb alloy with Tb precipitate particles with constant sizes and variation of volume concentration of the precipitates. Information about these alloys is available in the literature. The analysis has shown that, due to the coherent coupling of the Ti_3Ni_4 particles with the substrate, the temperature width of the transition R – B 19' depends on the particle sizes, which confirms the earlier established regularity of the local interior strain influence on this parameter. Concerning the NiMnGaTb alloy, the analysis has shown that, due to the presence of interior local strains associated with the Tb particles, the temperature width of the martensitic transformations increases linearly alongside the growth of the particle concentration in the alloy. The existence of the critical value of the particle concentration, above which the temperature width of the transition becomes indefinitely large, and the martensitic transformation in the alloy is blocked, is shown.