The effect of iron and silicon impurities on the phase composition and properties of the Al–4.3Cu–2.2Yb quasi-binary alloy has been determined. In the microstructure of the cast alloy, in addition to ...the aluminum solid solution and dispersed eutectic ((Al) + Al
8
Cu
4
Yb), in which about 1% of iron is dissolved, the Al
3
Yb/(Al,Cu)
17
Yb
2
and Al
80
Yb
5
Cu
6
Si
8
phases are identified, which are not found in an alloy of a similar composition without impurities. After homogenization annealing at a temperature of 590°C for 3 h, the structure is represented by compact fragmented and coagulated intermetallic compounds 1–2 μm in size and a solid solution (Al) with a maximum copper content of 2.1%. The hardness of the deformed sheets significantly decreases after 0.5 h and changes slightly up to 6 h of annealing at temperatures of 150–210°C. After annealing at 180°C for 3 h, a substructure with a subgrain size of 200–400 nm is formed in the alloy structure. The softening after annealing of the rolled sheets at temperatures up to 250°C occurs owing to the recovery and polygonization processes and above 300°C owing to recrystallization. After annealing for 1 h at 300°C, the recrystallized grain size is 7 μm. The grain size increases to 16 µm after annealing for 1 h at 550°C. The Al–4.3Cu–2.2Yb alloy with impurities has a conditional yield strength of 205–273 MPa, a tensile strength of 215–302 MPa, and a relative elongation of 2.3–5.6% in the rolled alloy after annealing. Iron and silicon impurities do not lead to the formation of coarse lamellar intermetallic phases and do not reduce the ductility of the investigated alloy.
The microstructure and change in strength of Al–4.5%Zn–4.5%Mg–1%Cu–0,12%Zr–0,1%Sc alloy during annealing after hot deformation in the temperature range 300–450°C are studied. It is established that ...recrystallization hardly occurs during annealing: at temperatures of 350°C and 400°C softening does not occur, which microstructural studies confirm. During annealing at 450°C yield strength is reduced by increasing the proportion of recrystallized volume to 15%. The structure formed after hot and cold rolling and subsequent annealing has a significant effect on sheet ageing kinetics compared with an ingot. The maximum effect of ageing in the sheet is observed after treatment at 125°C, whereas similar strengthening is achieved in an ingot at 150°C. Test alloy after hot and cold rolling, quenching and ageing at 125°C for 28 hours exhibits a high level of mechanical properties: yield strength 480 ± 5 MPa; ultimate strength 545 ± 7 MPa; relative elongation 6.3 ± 0.4%.
The microstructure and mechanical properties of the Al-4Cu-2.7Er-0.3Zr alloy were investigated. The precipitates of the L1
2
structured phase with sizes 37 ± 12 nm were formed in lines and ...homogenously distributed inside the aluminium matrix after annealing at 605°C for 1 h. The as-rolled Al-4Cu-2.7Er-0.3Zr alloy developed an increased hardness after 1 h annealing at 100-550°C and 0.5-6 h annealing at 150-250°C due to precipitation of the Al
3
(Er,Zr) phase. Addition of Zirconium improved the tensile properties relative to those of the Zr-free alloy by approximately 20 MPa: yield strength = 273-296 MPa and ultimate tensile strength = 296-328 MPa in the alloys annealed at 100-150°C.
The effect of impurities of Fe and Si on the microstructure and kinetics of the change in the hardness during annealing of the cast Al–0.2% Zr–0.1% Sc and Al–0.2% Zr–0.1% Sc–0.2% Y alloys has been ...studied. It has been found that the presence of the impurities of Fe and Si in the Al–0.2% Zr–0.1% Sc alloy leads to a partial binding of scandium into the (Al, Fe, Si, Sc) and (Al, Fe, Sc) phases of crystallization origin and to the corresponding depletion of the aluminum solid solution of Sc. It has been shown that as a result, the strengthening is significantly decreases upon annealing. The addition of 0.2% Y into the Al–0.2% Zr–0.1% Sc alloy with impurities of Fe and Si leads to the formation of the Al
3
Y and (Al, Y, Fe, Si) phases, whereas Sc is completely dissolved in the aluminum solid solution. It has been shown that the addition of Y leads to an increase in the thermal stability of the alloys during annealing at temperatures of 250, 300, and 370°C and eliminates the negative effect of impurities of Fe and Si.
The influence of ytterbium addition on the phase composition, strengthening upon annealing before and after rolling, and on the electrical conductivity and mechanical properties of the Al–0.2% ...Y–0.2Sc alloy has been investigated in this work. A dispersed eutectic, in which particles of an intermetallic phase with a size of 100–250 nm are enriched in yttrium and ytterbium, has been revealed in the cast structure apart from the aluminum solid solution. The maximum strengthening of the ingot is achieved after the annealing at 300°C for 3 hours due to the precipitation of Al
3
M dispersoids. The annealing of deformed sheets at 300°C results in an increase in the hardness and yield strength, which is connected with the initiation of the process of the additional decomposition of the aluminum solid solution. This means that the addition of ytterbium stimulates the heterogeneous nucleation of Al
3
M dispersoids in the post-rolling annealing process. In this case, according to the international standard for the annealed copper, the electrical conductivity increases with increasing temperature and time of annealing from 54 to 54.9% and to 57.7% after annealing at 200°C and 300°C, respectively.
The purpose of this research is to provide a competitive alternative to aluminum silicon alloys used in automotive applications. This alternate was created by developing composites of Al-5%Cu alloy ...reinforced with B4C particulates with a low coefficient of thermal expansion. Stir casting was used to produce Al-5%Cu alloys containing 2%, 5%, and 7%wt. B4C particulates were subsequently added using the squeeze casting process. The squeeze casting technique decreased the porosity of the final composites. The composites exhibited a fairly uniform particle distribution throughout the alloy matrix. The microstructure and the XRD results of the composites indicated that a significant reaction had occurred at the interface between the particles and the matrix. Increasing the aging temperature from 200 to 250°C decreased the hardness values of the matrix and the composites and decreased the time required to reach the peak. The coefficient of thermal expansion (CTE) for both the stir and squeezed cast samples decreased as the percentage of reinforcements increased and increased as the temperature range increased. Increasing the concentration of B4C increased YS and decreased the plasticity during compression test at both room and elevated temperatures. The Al-5%Cu-7%B4C composite has a significant higher tensile properties than A336 (AlSi12CuMgNi) at 260°C. Special mould made of 20Cr13 steel was constructed to evaluate castability. The Al-5%Cu-7%В4С composite completely repeats shape of the mould during squeeze casting process without hot cracking.
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Deformation behavior, microstructure and mechanical properties of Al–Cu–Yb(Gd)–Mg–Mn–Zr alloy sheets are investigated. Based upon results of processing maps, optimum regimes for thermomechanical ...treatment at temperatures of 490–540°C and speeds of 0.01–1 sec
–1
are determined. Annealing of cold-rolled sheets at temperatures up to 180°C leads to predominance of a strengthening effect due to aging over weakening from polygonization. Annealing of alloy sheets for 1 h at 400°C forms a partly recrystallized structure with a clear reduction in hardness from 145 HV to 75 HV. After 2 hours of annealing at 150°C, alloy combines a high yield strength of 412–417 MPa, a tensile strength of 441–449 MPa, and a good relative elongation of 2.7–3.2%. Sheet hardening followed by aging makes it possible to increase ductility by up to 5–8%, while the yield strength is 300–306 MPa with tensile strength of 364–389 MPa.
Specific features of the microstructure formation of an Al–2.5% Fe–1.5% Mn alloy owing to the cooling rate during casting and during laser melting are studied in this work. An analysis of the ...microstructure in the molten state shows that, with an increase in the cooling rate during crystallization from 0.5 to 940 K/s, the primary crystallization of the Al
6
(Mn,Fe) phase is almost completely suppressed and the volume of the nonequilibrium eutectic increases to 43%. The microstructures of the Al–2.5% Fe–1.5% Mn alloy after laser melting are characterized by the presence of crystals of an aluminum matrix of a dendritic type with an average cell size of 0.56 μm, surrounded by an iron-manganese phase of eutectic origin with an average plate size of 0.28 μm. The primary crystallization of the Al
6
(Mn,Fe) phase is completely suppressed. The formation of such a microstructure occurs at cooling rates of 1.1 × 10
4
–2.5 × 10
4
K/s, which corresponds to the cooling rates implemented in additive technologies. At the boundary between the track and the base metal and between the pulses, regions were revealed consisting of primary crystals of the Al
6
(Mn,Fe) phase formed by the epitaxial growth mechanism. The size of the primary crystals and the width of this zone depends on the size of the eutectic plates and the size of the dendritic cell located in the epitaxial layer. After laser melting, the Al–2.5% Fe–1.5% Mn alloy has a high hardness at room temperature (93 HV) and, after heating up to 300°C, it has a high thermal stability (85 HV). The calculated yield strength of the Al–2.5% Fe–1.5% Mn alloy after laser melting is 227 MPa. The combination of its ultrafine microstructure, high processibility during laser melting, hardness at room and elevated temperatures, and high calculated yield strength make the Al–2.5% Fe–1.5% Mn alloy a promising alloy for use in additive technologies.
Laws of the formation of substructure and of changes in the hardness and in the mechanical properties have been established for sheets of 1545K alloy obtained by tension according to different ...technologies at various accumulated strains. With an increase in cold deformation (
e
cold
) from 0 to 2.64, the yield stress of cold-worked sheets increases from 355 to 466 МPа and the relative elongation decreases insignificantly from 4 to 3.5%. The maximum strength with σ
0.2
= 410 МPа, σ
u
= 460 МPа, and δ = 6.5% is provided by annealing at 150°C for 1 h of the sheets obtained via the technology with the maximum fraction of cold deformation (
e
cold
= 2.64). After annealing at 300°C for 30 min, a twofold increase in the plasticity is observed without a significant reduction in the strength characteristics a follows: σ
0.2
= 385 МPа, σ
u
= 436 МPа and δ = 13%. It has been shown that the level of mechanical properties is determined by the substructure that is formed inside deformed grains during annealing.
Under mechanical stirring, 5% of B4C ceramic particles were added to Al-5%Cu-0.8Mn matrix alloy subsequently, the produced composites were re-melted and squeezed using squeeze casting route. ...Microstructure evolution was characterized using TEM, SEM and XRD analyses. 0.8Mn were added to Al-5%Cu-5%B4C to investigate their effect on thermal expansion coefficient (CTE). The matrix along with its composites were tested by compression test at room and elevated temperatures. At room and 200 °C compression test temperatures, the addition of Mn to the composites lead to YS improvement from 248 to 360 MPa and from 190 to 242 MPa at room and 200 °C temperatures respectively. The addition effect of 0.8Mn on the strain rate , % was more pronounced at high temperature. The creep rupture test was performed for one hour and 260 °C at different constant stresses after wards, the creep fracture surfaces were examined by SEM analysis. As compared with A355 piston alloy, the Al-5%Cu-0.8Mn-5%B4C composites showed more creep resistance allowing it to be a suitable replacement for A355 alloy in automotive industries. The experimental and simulated creep results were compared with each other to investigate the integrity of the actual results with simulated one, the result as well found to be fairly integrated and similar.
