Experimental Investigation of the Phase Relations in the Fe-Zr-Y Ternary System

The phase relations of the Fe-Zr-Y system at 973 K and 1073 K were experimentally investigated by using the equilibrated alloys. New ternary compounds τ3-Fe3ZrY and τ4-Fe10Zr5Y2 were found in this ternary system. The solubility of Y in Fe2Zr was measured to be 3.5 at.% and the third component can hardly dissolve in the other binary intermetallic phases. Experiments have verified that Fe2.9Zr0.5Y0.5 has a solid solubility ranging from Fe73Zr12Y14 to Fe77Zr9Y13.

Role of Iron-Rich Phases and Porosity on the Ductility of Rheocast Al-Mg-Si-Alloys

Treatment of the slurry is important during RheoMetalTM casting. In this work, semi-solid slurries were prepared under different stirring intensities, using two types of stirrers: a naked rod (for regular stirring) and a rod with two blades (for intensified stir). Tensile tests were performed, investigating fracture surfaces, as well as metallographic samples. The results show that intensified stir produces castings with finer primary particles and a more homogeneous microstructure. On the other hand, more faceted Fe-rich phases are found along the α-Al grains boundary as well, due to the dissolution of Fe from the stirrers. Moreover, for intensified stir castings, the porosity found on the fracture surfaces are smaller, while more brittle eutectic phases and second (intermetallic) phases, especially Fe-rich phases, are observed. Consequently, the castings with intensified stir show worse ductility. Finally, a quantitative analysis was made regarding ductility, affected both by porosity and the presence of Fe-rich phases.

Intermetallic Phases Identification and Diffusion Simulation in Twin-Roll Cast Al-Fe Clad Sheet

Aluminium steel clad materials have high potential for industrial applications. Their mechanical properties are governed by an intermetallic layer, which forms upon heat treatment at the Al-Fe interface. Transmission electron microscopy was employed to identify the phases present at the interface by selective area electron diffraction and energy dispersive spectroscopy. Three phases were identified: orthorhombic Al5Fe2, monoclinic Al13Fe4 and cubic Al19Fe4MnSi2. An effective interdiffusion coefficient dependent on concentration was determined according to the Boltzmann–Matano method. The highest value of the interdiffusion coefficient was reached at the composition of the intermetallic phases. Afterwards, the process of diffusion considering the evaluated interdiffusion coefficient was simulated using the finite element method. Results of the simulations revealed that growth of the intermetallic phases proceeds preferentially in the direction of aluminium.

Investigation of wear conditions of a composite material based on an anti-friction alloy AO20-1 reinforced with Ti particles

Сomposite material samples were obtained by the method of reaction casting by mixing titanium particles to obtain intermetallic phases Al3Ti. Dry sliding wear tests were carried out using a fixed sleeve (steel 45) against a rotating disk (sample) at sliding speeds from 0.25 to 0.75 m/s and loads from 0.5 to 3.5 MPa.There were constructed maps of wear rate, which determine the friction modes during testing. There were shown boundaries and conditions of changing wear modes.

On the probability of formation of intermetallic compounds in dissimilar welded joints obtained by friction stir welding

The article describes the mechanisms and causes of the occurrence of intermetallic phases during friction stir welding of dissimilar joints. The nucleation and growth of intermetallic phases for a pair of dissimilar metals to be welded under comparatively favorable time and temperature conditions of the FSW is facilitated by the atomic-vacancy environment, which is responsible for the continuous atomic-structural bond and mass transfer of accumulated atoms in local regions of the welded joint with an equiaxial grain lamella-shear structure of the welded core. compounds with a concentration close to critical, combined with others in a superplastic state. In the process of forming a welded joint under the influence of a moving and rotating welding tool, the lamellae are subjected to bending and torsional stresses with simultaneous tension, causing them to generate point defects and especially a large number of various types of dislocations, triggering the formation of edge dislocations in the lamellae, which are lined up in the process into dislocation walls, dividing lamella grains into separate fragmentary subgrain boundaries, along which the processes of fragmentation and dispersion develop. This phenomenon is explained by the fact that the processes of fragmentation and dispersion of IMP lead to the composition of the nugget of the welded joint by fragments, often nano-sized fragments of various configurations, which act as hardeners of the weld nugget matrix.

Application of Nanosilicon to the Sintering of Mg-Mg2Si Interpenetrating Phases Composite

The new in situ fabrication process for Mg-Mg2Si composites composed of interpenetrating metal/intermetallic phases via powder metallurgy was characterized. To obtain the designed composite microstructure, variable nanosilicon ((n)Si) (i.e., 2, 4, and 6 vol.% (n)Si) concentrations were mixed with magnesium powders. The mixture was ordered using a sonic method. The powder mixture morphologies were characterized using scanning electron microscopy (SEM), and heating and cooling-induced thermal effects were characterized using differential scanning calorimetry (DSC). Composite sinters were fabricated by hot-pressing the powders under a vacuum of 2.8 Pa. Shifts in the sintering temperature resulted in two observable microstructures: (1) the presence of Mg2Si and MgO intermetallic phases in α-Mg (580 °C); and (2) Mg2Si intermetallic phases in the α-Mg matrix enriched with bands of refined MgO (640 °C). Materials were characterized by light microscopy (LM) with quantitative metallography, X-ray diffraction (XRD), open porosity measurements, hardness testing, microhardness testing, and nanoindentation. The results revealed that (n)Si in applied sintering conditions ensured the formation of globular and very fine Mg2Si particles. The particles bonded with each other to form an intermetallic network. The volume fraction of this network increased with (n)Si concentration but was dependent on sintering temperature. Increasing sintering temperature intensified magnesium vaporization, affecting the composite formation mechanism and increasing the volume fraction of silicide.