The microstructure and properties of the novel heat resistant Al–3Ce–7Cu alloy produced by selective laser melting were investigated. Fine Al
11
Ce
3
and Al
6.5
CeCu
6.5
eutectic phases were found in ...the microstructure. Annealing at temperatures in the 250–400 °C range leads to a decrease in the hardness. Hardness has larger values after annealing at 350 and 400 °C than at 250 °C due to the precipitation of nanosized particles. The low hardness after quenching and aging at 190 °C is caused by quench stress relief and the absence of aging hardening because of poor solid solution. The as-printed yield strength, ultimate tensile strength and elongation are 274 MPa, 456 MPa and 4.4%, respectively. High mechanical properties of the Al–3Ce–7Cu alloy were demonstrated by high temperature tension and compression tests.
The microstructure and mechanical properties of new high-temperature casting aluminum alloys Al–5.6Cu–2.0Y–1Mg–0.8Mn–0.3Zr–0.15Ti–0.15Fe–0.15Si and ...Al–5.4Cu–3.0Er–1.1Mg–0.9Mn–0.3Zr–0.15Ti–0.15Fe–0.15Si are investigated. In an alloy with yttrium, modification with titanium gives rise to a decrease in the grain size from 190 to 40 μm, while the grain size in an alloy with erbium is 25 μm. Regarding the casting properties, the alloys are comparable to silumins alloyed with copper and magnesium. The greatest strengthening effect after quenching is achieved with aging at 210°C; the hardness is 130–133 HV. The tensile yield point at room temperature is 303–306 MPa with a relative elongation of 0.4%. At elevated temperatures of 200 and 250°C, the yield stress decreases to 246–250 and 209–215 MPa, and the elongation increases to 3 and 4–5.5%, respectively. The long-term strength retention after 100 h exposure to 250°C is 117–118 MPa. The presence of a solid solution that is sufficiently alloyed and strengthening dispersoids of the Al
3
(Zr,Er), Al
3
(Zr,Y), and Al
20
Cu
2
Mn
3
phases and the Al
8
Cu
4
Y, (Al,Cu)
11
Y
3
, (Al,Cu,Y,Mn), Al
8
Cu
4
ErAl
3
Er, and (Al,Cu,Er,Mn) phases of crystallization origin in new alloys provide high levels of heat resistance.
This paper studies the effect of the laser melting process (LMP) on the microstructure and hardness of a new modified AlCuMgMn alloy with zirconium (Zr) and Yttrium (Y) elements. Homogenized (480 ...°C/8 h) alloys were laser-surface-treated at room temperature and a heating platform with in situ heating conditions was used in order to control the formed microstructure by decreasing the solidification rate in the laser-melted zone (LMZ). Modifying the AlCuMgMn alloy with 0.4 wt% Zr and 0.6 wt% Y led to a decrease in grain size by 25% with a uniform grain size distribution in the as-cast state due to the formation of Al
(Y, Zr). The homogenization dissolved the nonequilibrium intermetallic phases into the (Al) matrix and spheroidized and fragmentized the equilibrium phase's particles, which led to the solidification of the crack-free LM zone with a nonuniform grain structure. The microstructure in the LMZ was improved by using the in situ heating approach, which decreased the temperature gradient between the BM and the melt pool. Two different microstructures were observed: ultrafine grains at the boundaries of the melted pool due to the extremely high concentration of optimally sized Al
(Y, Zr) and fine equiaxed grains at the center of the LMZ. The combination of the presence of ZrY and applying a heating platform during the LMP increased the hardness of the LMZ by 1.14 times more than the hardness of the LMZ of the cast AlCuMgMn alloy.
The structure and properties of new wrought aluminum Al–4.5Cu–1.6Y–0.9Mg–0.6Mn–0.2Zr–0.1Ti–0.15Fe–0.15Si and Al–4.0Cu–2.7Er–0.8Mg–0.8Mn–0.2Zr–0.1Ti–0.15Fe–0.15Si alloys are studied. After ...homogenization and rolling, the structure is formed, which consists of the aluminum-based solid solution strengthened with fine Al
3
(Zr,Er), Al
3
(Zr,Y), and Al
20
Cu
2
Mn
3
phase particles and compact thermally stable phases of solidification origin 1–5 µm in size. The recrystallization after rolling occurs at temperatures above 350°С. As the annealing temperature increases from 400 to 550°С, the recrystallized grain size increases from 6–8 to 10–12 µm. At temperatures of 150–180°С, the hardness increases after 2-h annealing; this is related to the occurrence of aging, and the analogous effect was observed for the cast alloys of these systems. The yield strength of the Y-containing alloy subjected to 6-h annealing at 150°С is 405 MPa; in this case, the relative elongation is 4.5%. As the annealing temperature increases to 210°С, the yield strength of the both alloys decreases to 300 MPa, whereas the relative elongation remains unchanged. In the case of the alloys quenched after rolling and subsequently aged at 210°С, the yield strength of 264–266 MPa and ultimate tensile strength of 356–365 MPa are reached at a relative elongation of 11.3–14.5%. As a result, the new wrought Al–Cu–Y- and Al–Cu–Er-based alloys provide competition for the available industrial alloys.
The evolution of the microstructure and mechanical properties of quasibinary Al–6.5Cu–2.3Y and Al–6Cu–4.05Er alloys during homogenization and subsequent thermomechanical treatment has been studied in ...this work. The Cu concentration in the aluminum solid solution increases during homogenization before quenching owing to the dissolution of a nonequilibrium excess of phases of crystallization origin and is 1.8 and 2.3% for the alloys containing Y and Er, respectively. The size of intermetallic phases in the Al–6.5Cu–2.3Y and Al–6Cu–4.05Er alloys homogenized at 605°С for 3 hours is 1.2 and 0.75 μm, respectively, and does not increase significantly with an increased annealing time. The Al–6Cu–4.05Er alloy is less prone to softening during annealing after rolling than the Y-containing alloy. This is explained by a greater degree of alloying of the aluminum solid solution (Al) and by a greater degree of dispersity of phases of crystallization origin. However, because of the same factor, the Er-containing alloy has a higher inclination to recrystallization and thereby a coarser recrystallized grain. As a result, the Al–6Cu–4.05Er alloy demonstrates higher mechanical tensile characteristics, especially after annealing at temperatures above 150°С.
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The development of modern computational techniques and equipment enables one to perform high-precision calculations of complex processes for industry, including metallurgy. This review has ...classified the basic physical and mathematical models of structure formation during heat and deformation treatment. The Kocks–Mecking–Estrin model describing the dislocation structure at the initial stage of hot plastic deformation has been analyzed. The models of dynamic, metadynamic, and static recrystallization kinetics based on the Johnson–Mehl–Avrami–Kolmogorov equation have been considered. The models of the kinetics of phase transformation upon heating and cooling of steel have been reviewed. The Kampmann–Wagner model that describes the decomposition of supersaturated solid solution during the aging of aluminum alloys has also been considered. The main computational techniques to calculate microstructural evolution, such as the cellular automaton, Monte Carlo, and multiphase-field techniques have been considered. They exhibit high accuracy when calculating recrystallization processes and phase transformations. The systematization of the existing models that describe structural evolution has revealed the possibility to develop complex models for the comprehensive calculation of full cycles to process metal materials by heating and deformation. These models can be used for the optimization and development of new processing techniques.
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The effect of manganese on the microstructure, phase composition, and mechanical properties of the heat-strengthened deformed Al–5.5Cu–2.0Y–0.3Zr alloy has been studied in this work. The structure ...of the cast alloy was shown to contain a quaternary phase enriched in copper, manganese, and yttrium with a Cu/Mn/Y ratio of 4/2/1, which corresponds to the chemical compound Al
25
Cu
4
Mn
2
Y. The maximum strengthening of the ingot was achieved by aging after quenching at 210°C for 5 h. Three types of precipitates, Al
20
Cu
2
Mn
3
and Al
3
(Zr,Y), were formed in the heat-treated structure in the course of homogenization at 605°C. The size of Al
3
(Zr,Y) particles was 30–50 nm. The Al
20
Cu
2
Mn
3
phase had a longitudinal size of 200–250 nm and a transverse size of 150–200 nm. The disc-shaped precipitates of the θ''(Al
2
Cu) metastable phase with a diameter of 80–200 nm and a thickness of about 5 nm formed upon aging. After rolling and annealing for 1 and 2 h, the hardness was maximum at 150°C. This was explained by a predominance of aging over softening, which retards the growth of dispersoids of Al
20
Cu
2
Mn
3
and Al
3
(Zr,Y) phases and dispersed Al
8
Cu
4
Y and (Al,Cu)
11
Y
3
particles of crystallization origin. At 210°C, the softening of deformed alloy prevails over the effect of aging and as a result, the hardness decreases slightly. The addition of manganese makes it possible to retain a significantly high hardness in the studied alloy at annealing temperatures up to 550°С and to increase the temperature of the onset of recrystallization to 350–400°С. After rolling followed by annealing at 150°C the alloy was shown to possess high mechanical properties: σ
0.2
= 330–334 MPa, σ
u
= 374 MPa, and δ = 3.6–5.5%.
Thermodynamic calculations, scanning electron microscopy, X-ray diffraction analysis, and differential scanning calorimetry have been used to study the phase composition of a Al–Zn–Mg–Cu–Zr alloy ...that is rich in copper, which was additionally alloyed with yttrium or erbium. There are (Al), T, Al
8
Cu
4
Y, and AlMgY phases of solidification origin in the AlZnMgCuZrY alloy. The erbium-bearing AlZnMgCuZrEr alloy contains three additional intermetallic phases in addition to the T phase: two intermetallic phases with a composition close to the Al
8
Cu
4
Er phase and one of the Al
3
Er composition. One of the Al
8
Cu
4
Er-phase particles contains approximately 2 wt % Fe. Aging at 150°C led to a greater increment in the hardness of the erbium alloy, while the hardness level achieved is the same for all alloys under study. Overaging at 210 and 250°C takes place significantly earlier in the alloy without yttrium and erbium additives, given the same level of hardening. Taking the fact into account that the kinetics of aging depend mainly on the (Al) composition, the differences in kinetics in the alloys with additions can be explained by dispersoids formed during homogenization before quenching and the solid solution depleted of the main elements (zinc, magnesium, and copper). The yield strength of the alloys with yttrium and erbium additives is insignificantly lower at high temperatures, which is likely due to the lower alloying of the aluminum matrix. However, these alloys are of a better technological effectiveness at casting.
The mechanical properties and microstructure of as-cast and homogenized AA7075 were investigated. This alloy was modified by adding transition elements 0.3%Sc + 0.5%Zr, 1%Ti + 0.2%B, and 1%Fe + 1%Ni ...for use in additive manufacturing applications. After adding Ti + B and Sc + Zr, the structure became uniform and finer with the formation of the Al3(Sc, Zr) and TiB2 phases. Coarse structures were obtained with the formation of an extremely unfavorable morphology, close to a needle-like structure when Fe + Ni was added. The mechanical properties of the modified alloys were increased compared to those of the standard alloy, where the best ultimate tensile strength (UTS) and yield strength (YS) were obtained in the AA7075-TiB alloy compared to the standard alloy in as-cast and homogenized conditions, and the highest hardness value was provided by Fe + Ni additives. The effect of the laser melting process on the microstructure and mechanical properties was investigated. Single laser melts were performed on these alloys using 330 V and a scanning speed of 8 mm/s. During the laser melting, the liquation of the alloying elements occurred due to non-equilibrium solidification. A change in the microstructures was observed within the melt zone and heat-affected zone (HAZ). The hardness of the laser-melted zone (LMZ) after adding the modification elements was increased in comparison with that of the standard alloy. Corrosion testing was performed using a solution of 100 mL distilled water, 3.1 g NaCl, and 1 mL HCl over 5, 10, and 30 min and 1 and 2 h. The corrosion resistance of the alloy modified with FeNi was low because of the non-uniform elemental distribution along the LMZ, but in the case of modification with ScZr and TiB, the corrosion resistance was better compared to that of the standard alloy.
The effect of impurities on the phase composition and properties of a wrought alloy of the Al–Cu–Er system has been investigated in this work. According to the results of the scanning electron ...microscopy and X-ray diffraction analysis, Al
8
Cu
4
Er, Al
3
Er, and Al
3
Er
2
Si
2
particles of phases of crystallization origin are present in the structure of the alloy. After annealing at 605°C, the Al
8
Cu
4
Er and Al
3
Er phases have compact morphology close to spherical with a maximum size of particles up to 3 μm, and the Al
3
Er
2
Si
2
phase has a needle shape with a length of up to 15 μm. No needle-shaped particles have been detected in the structure after rolling, which indicates the fragmentation of the Al
3
Er
2
Si
2
phase. Iron and silicon impurities do not have a significant effect on the alloy recrystallization, but somewhat increase its hardness after annealing at low temperatures (to 250°C). After annealing at 100 and 150°C, the investigated alloy shows a sufficiently high level of mechanical properties: according to the results of tests for uniaxial tension, its proof stress is 277–310 MPa and the ultimate strength is 308–350 MPa, which is 10–30 MPa more than that in the alloy without impurities.
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