The composites of 6063 + 5%B4C and 1545 K + 5%B4C were successfully produced by two stir casting techniques. The first involved incorporation of reinforcements particles in pure form. Stir casting ...technique was novel, in which the particles incorporated to the melt using by powder master alloy. The incorporation of B4C particles in pure form is more effective than using a powder master alloy. A good interface reaction between the matrix and the B4C reinforcements was observed by the formation of Al3BC and AlB2 phases on the matrix/B4C interface. 1545 K + 5%B4C alloy showed YS = 425 MPa and UTS = 455 MPa and, also high resistance to intercrystalline corrosion.
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•The MMC of 6061 + 4%B4C and 1545 K + 4%B4C were successfully produced by stir casting techniques.•Novel stir casting technique was used - the particles incorporated to the melt by powder master alloy.•Good interface reaction between the matrix and the B4C reinforcements was observed.•The formation of Al3BC and AlB2 phases on the matrix/B4C interface was demonstrated.•1545 K + 4%B4C MMC showed YS = 425 MPa and UTS = 455 MPa and high resistance to intercrystalline corrosion.
The purpose of this research is to develop and characterize composites of Al-5%Cu alloy reinforced by silicon and boron nitride (Si3N4, BN). The developing of this type of composites gives a new ...trend of metal matrix composite synthesizing, especially in the case of boron nitride. The stir cast composites showed large areas of porosity and agglomeration. On the other hand, the squeezed cast composites exhibited a fairly uniform particles distribution throughout the matrix alloy. The microstructure and XRD results of the composites confirmed a reaction occurred at the interface between the particles and alloy. AlN and AlB2 phases were identified in Al5%Cu-Si3N4 and Al5%Cu-BN composites respectively. The ageing results showed that the time to reach peak hardness decreased with addition of the particles. Also, the ageing kinetics was significantly accelerated due to the presence of BN particulates. The coefficient of thermal expansion (CTE) results of the matrix alloy and its composites were practically and theoretically determined. Difference between experimental and calculated values of CTE was less than 8%. Increasing the concentration of Si3N4 increased YS from 215MPa in the matrix alloy to 285MPa in the Al-5%Cu-7%Si3N4 composites at a testing temperature of 20°C.
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•The novel MMCs Al5Cu-Si3N4/BN successfully produced by squeeze casting techniques•Squeeze casting technique improves the wettability between the matrix and nitrides.•XRD analysis showing the presence of new AlN and AlB2 phases•The hardness curves of the MMCs exhibited the increasing trend till reaching peak.•BN reinforcements significantly accelerate precipitation behavior of Al-5%Cu alloy.
The possibility of determining the hot cracking index using the calculated value of the effective solidification range is investigated for multicomponent cast aluminium alloys based on the Al-Mg-Zn ...system with Mn, Ni, Fe and Si additives. The upper limit of the effective solidification range was calculated as the temperature of formation of a 65 wt-% solid phase using the Sheil model. The linear relationship of the hot cracking index and the effective solidification range in the industrial and experimental multicomponent alloys based on the Al-Mg-(Zn) system is demonstrated.
The mechanical properties and microstructure of sheets of an Al–4.7Mg–0.32Mn–0.21Sc–0.09Zr alloy deformed and annealed after rolling have been investigated. The total accumulated true strain was ε
f
...= 3.33–5.63, and the true strain at room temperature and at 200 °C was ε
с
= 0.25–2.3. The strength properties of the sheets (yield stress σ
0.2
= 495 MPa and ultimate tensile strength σ
u
= 525 MPa) in the deformed state were greater than those after equal-channel angular pressing (ECAP) deformation. The mechanical properties of the deformed sheets after annealing depended on the size of subgrains inside the deformed grains bands with high-angle grain boundaries (HABs). With the increase in the annealing temperature from 150 to 300°С, the subgrain size increased from 80 to 300 nm. The relative elongation δ in the as-cast state and after annealing at 200–250°C (δ = 40–50%) was higher than that after annealing at 300–370°C (δ = 24–29%).
Steels with high boron content are important materials to produce spent nuclear fuel storage. The large volume fraction of brittle borides in the high boron steel microstructure makes it very hard ...and not easily deformable. Preliminary investigation and simulation of the hot deformation behavior is a necessary step for the development of industrial forming technologies. Hot compression tests of high boron steels with 2.05 and 3.15 wt% of boron, respectively were performed in the temperature range of 800–1150 °C on a Gleeble 3800 testing system. Based on the experimental true stress – true strain data, the strain-compensated Arrhenius-type constitutive models were applied for both steels. The model for the steel with 2.05 wt% of boron was approved by additional compression tests and by finite element simulation. The effective activation energy of the high boron steel deformation decreased with an increasing of the volume fraction of the borides due to the particle stimulated nucleation on the borides-ferrite interface.
Using the numerical simulation in the CA-FE module of the ProCAST simulation program, a systematic investigation of competitive growth of grains in a thin plate has been performed over a wide range ...of values of the temperature gradient and solidification rate. It has been established that the result of the simulation in the case of converging grains depends on the only parameter, i.e., the ratio of the value of the overgrowth of the grain with the preferred orientation to the size of the cell of the computational grid. Thus, the size of the cell is an important adjusting parameter of the model and must be coordinated with the parameters of the dendritic structure under given growth conditions. The grain with the preferred orientation always displaces neighboring diverging grains. The converging grains are eliminated if their deviation from the vector of the temperature gradient exceeds 20°. At the smaller angles of deviation, the result of the competitive growth depends on the size of the computational cell and varies from their joint growth (at the cell size of 5 μm) to the displacement of grains with the preferred orientation (at the cell size of 20 μm). However, all of the results of the simulation agree with the experimental data available in the literature. For the efficient selection of grains with the preferred orientation, regimes with a low temperature gradient and high growth rate are favorable.
The effect of the high-energy synthesis of powder mixtures of aluminium granules, ferrophosphorous (Fe2P) and strontium salt (SrCO3) in a planetary mill was investigated on the structure of the ...resulting materials. Al–8Fe–2P, Al–10Sr and Al–10Sr–1P master alloys were synthesised, and the efficiency of these new alloys was demonstrated in the modification of an eutectic silicon in Al–12Si alloys and the complex modification of Al–18Si alloys.
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•New powder master alloys were synthesised in a planetary mill Retsch PM 400.•The effect of the high-energy synthesis of powder mixtures was investigated.•The efficiency of the modification of eutectic silicon was demonstrated.•The efficiency of the complex modification of Al–18Si alloys was demonstrated.
The direct laser deposition of metal powders is one additive method of producing functional materials. It consists of the melting of metallic powders by a laser beam in inert gas. The main process ...parameters are the laser-beam power, laser-beam speed and scanning trajectory, and powder consumption. Each parameter is selected depending on the alloy type, which in totality affects the structure and defect formation in products. In this study, experimental rectangular samples of 316L austenitic steel are fabricated by the direct laser deposition of the powder. The microstructure and fractures of samples are investigated using scanning electron microscopy in order to determine the structural features and reveal the defects (pores, holes, crystallization cracks, and oxide inclusions). Uniaxial tension tests and hardness tests are performed. The analysis of the influence of the laser beam scanning trajectory on the microstructure and properties of samples during melting is performed. It is found that a dispersed structure with an average crystallite size of 1.3–1.9 μm is formed at a laser power of 250 W and scanning rate of 16 mm/s, which results in a high level of mechanical properties of experimental samples. It is shown that, when using the lengthwise laser-beam trajectory (along the largest sample size), the tensile strength reaches 730 MPa with a relative elongation of 25%, which exceeds the level of mechanical properties of 316L steel by 110 MPa.
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