Structure and Properties of Ca and Zr Containing Heat Resistant Wire Aluminum Alloy Manufactured by Electromagnetic Casting

: Experimental aluminum alloy containing 0.8% Ca, 0.5% Zr, 0.5% Fe and 0.25% Si (wt.%), in the form of a long-length rod 12 mm in diameter was manufactured using an electromagnetic casting (EMC) technique. The extremely high cooling rate during alloy solidiﬁcation ( ≈ 10 4 K/s) caused the formation of a favorable microstructure in the ingot characterized by a small size of the dendritic cells, ﬁne eutectic particles of Ca-containing phases and full dissolution of Zr in Al the solid solution. Due to the microstructure obtained the ingots possess high manufacturability during cold forming (both drawing and rolling). Analysis of the electrical conductivity (EC) and microhardness of the cold rolled strip and cold drawn wire revealed that their temperature dependences are very close. The best combination of hardness and EC in the cold rolled strip was reached after annealing at 450 ◦ C. TEM study of structure evolution revealed that the annealing mode used leads to the formation of L1 2 type Al 3 Zr phase precipitates with an average diameter of 10 nm and a high number density. Experimental wire alloy has the best combination of ultimate tensile strength (UTS), electrical conductivity (EC) (200 MPa and 54.8% IACS, respectively) and thermal stability (up to 450 ◦ C) as compared with alloys based on the Al–Zr and Al– rare-earth metal (REM) systems. In addition, it is shown that the presence of calcium in the model alloy increases the electrical conductivity after cold forming operations (both drawing and rolling).


Introduction
For many years, electrical engineering applications have been recognized as one of the main uses of aluminum in terms of industry economics, which is constantly developing under the current widespread tendency for replacing copper conductors [1]. Most conductive Al alloys are related to 1xxx (Al-Fe-Si), 6xxx (Al-Mg-Si) and 8xxx (Al-Fe) families. For manufacturing electrical parts with appropriate parameters, continuous casting and rolling are currently used for shaping and deformation strengthening. However, the latter is highly reduced after heating to above~250 • C due to recrystallization.
For the sake of both improving heat resistance and operating temperature, Al-Zr alloys have been developed for particular applications, like overhead cables for long-distance obtain the wire (3 mm diameter, see in Figure 1b). The obtained wire was subjected annealing at 350-450 °C together with the 2 mm strip (Figure 1a) made additionally fr the as-cast EMC rod by cold rolling (using a Chinetti LM160 laboratory-scale rolling m machine). This strip was prepped for the analysis of the influence of deformation on decomposition of (Al) during annealing. The stepwise annealing modes ( Table 2) used all experimental samples (EMC rod, wire and strip) were previously substantiated [2 The Vickers hardness and electrical conductivity (EC) of the samples were measured each annealing step. The measurement was carried out at room temperature.

Designation Regime Treatment R-EMC casting rod (diameter 12 mm)/S-cold rolled strip (thickness 2 mm) R/S
As-cast/as-cold rolled R300/S300 Annealing at 300 °C, 3 h R350/S350 R300/S300 + annealing at 350 °C, 3 h R400/S400 R350/S350 + annealing at 400 °C, 3 h R450/S450 R400/S400 + annealing at 450 °C, 3 h R500/S500 R450/S450 + annealing at 500 °C, 3 h   The as-cast EMC rod was processed using drawing (the reduction ratio was 94%) to obtain the wire (3 mm diameter, see in Figure 1b). The obtained wire was subjected to annealing at 350-450 • C together with the 2 mm strip ( Figure 1a) made additionally from the as-cast EMC rod by cold rolling (using a Chinetti LM160 laboratory-scale rolling mill machine). This strip was prepped for the analysis of the influence of deformation on the decomposition of (Al) during annealing. The stepwise annealing modes (Table 2) used for all experimental samples (EMC rod, wire and strip) were previously substantiated [22]. The Vickers hardness and electrical conductivity (EC) of the samples were measured at each annealing step. The measurement was carried out at room temperature.
Besides, the ternary and 4 quaternary alloys containing 0.5% Fe, 0.25% Si and up to 1% Ca were prepared to estimate the effect of calcium on the electrical conductivity. These alloys were poured at 750 • C into a flat graphite mold (of 10 mm × 40 mm × 180 mm in size). The cold rolled sheet products of 2 mm thickness were prepared from as-cast ingots.
The microstructure was studied using scanning electron microscopy (SEM, TESCAN VEGA 3, Tescan Orsay Holding, Brno, Czech Republic), electron microprobe analysis (EMPA, OXFORD Aztec, Oxford Instruments, Oxford shire, UK), and transmission electron microscopy (TEM, JEM 2100, JEOL, Tokyo, Japan). Mechanical polishing was used together with electrolytic polishing, which was carried out at a voltage of 15 V at a temperature of −25 • C in an electrolyte containing 20% nitric acid and 80% methanol. The thin foils for TEM were prepared by ion thinning with a PIPS (Precision Ion Polishing System, Gatan, Pleasanton, CA, USA) machine and studied at 160 kV.
Tensile tests for as-processed wire specimens were conducted by using a universal testing machine, model Zwick Z250 (Zwick Roell AG, Ulm, Germany). The Vickers hardness (HV) was measured using a MetkonDuroline MH-6 (METKON Instruments Inc., Bursa, Turkey) universal tester. A load of 1 kg and a holding time of 10 s were used to determine the Vickers hardness. The hardness was measured at least five times at each point.
The specific electrical conductivity (EC) of the EMC rod and the cold rolled strip was determined using the eddy current method with a VE-26NP eddy structures instrument (CJSC Research institute of introscopy SPEKTR, Moscow, Russia). The electrical resistivity of the cold drawn wire was measured for straightened samples of at least 1 m in length in the rectified part (in accordance with IEC 60468:1974 standard [28]).

Characterization of as-Cast Structure
The extremely high cooling rate during ACZ alloy solidification caused the formation of a favorable microstructure (Figure 2a) characterized by small size of dendritic cells, fine eutectic particles of Ca-containing phases and full dissolution of Zr in Al solid solution. The measured average size of the dendritic cells is~4 µm (Figure 2b) which, according to other studies [22,29,30], corresponds to a cooling rate of~10 4 K/s. Calcium-bearing eutectic particles corresponding to the quaternary eutectic (Al) + Al 4 Ca + Al 10 CaFe 2 + Al 2 CaSi 2 [26] are detected in the form of thin veins located along the boundaries of the aluminum dendritic cells. It should be noted that the as-cast structure does not contain needle-shaped inclusions, for example, iron-containing ones.
Remelting of EMC rod followed by pouring into a graphite mold (cooling velocity about 20 K/s) leads to coarsening of structure and the formation of some needle-like particles (Figure 2c). On the other hand, the structure of the alloy after slow solidification (in a furnace) differs considerably from that of the initial EMC rod. Along with the expected general coarsening of the structure, the phase composition of the alloy changes. In particular, needle-shaped Al 3 Fe phase inclusions and segregation of primary Al 3 Zr phase crystals ( Figure 2d) that are absent in the EMC rod structure can be identified (Figure 2a,b) after slow solidification.
As expected, cold deformation leads to a hardening of the ACZ alloy-the hardness increases up to 65HV for strip and up to 70 HV for wire (states R and W, respectively, see Table 3). A surprising result is a significant increase in the electrical conductivity-up to ~ 25 MS/m (both for strip and wire). In an earlier study for a Ca-free Al-0.6% Zr-0.4% Fe-0.4% Si alloy obtained by a similar process, this effect was not observed [22]. According to EMC rod hardness data obtained during annealing (Figure 4a), hardening reaches the highest level at 450 °C annealing stage temperature (the R450 state). Further increase in the annealing temperature leads to a significant decrease in HV, which is mainly due to the coarsening of the Al3Zr precipitates [5][6][7][8][9][10][11]16]. Deformation hardening was retained upon strip annealing to 450 °C. At this temperature, the hardness of the EMC rod is the same as for the cold rolled strip (Figure 4a). Further increase in the annealing temperature leads to a significant softening due to the formation of a recrystallized structure. At the maximum annealing temperature used, 600 °C, they had approximately the  Table 2), (c)~20 K/s (10 mm × 40 mm × 200 mm ingot), (d)~0.1 K/s (cooling in furnace).

Effect of Cold Deformation and Annealing on Structure, Hardness and Electrical Conductivity
Due to the fine structure of the eutectic, the as-cast EMC rod possesses high ductility, even during cold forming. During both rolling and drawing, apart from the formation of a fibrous grain structure, fragmentation of Ca-containing eutectic particles can also be observed. Their size is not greater than 1 micron and they are uniformly distributed in the aluminum matrix (Figure 3a,b). Annealing at up to 450 • C inclusively does not lead to a significant change in the size of Ca-containing eutectic particles. However, the structure remains non-recrystallized. Coarsening of particles is observed at higher temperatures (Figure 3c,d).
As expected, cold deformation leads to a hardening of the ACZ alloy-the hardness increases up to 65HV for strip and up to 70 HV for wire (states R and W, respectively, see Table 3). A surprising result is a significant increase in the electrical conductivity-up tõ 25 MS/m (both for strip and wire). In an earlier study for a Ca-free Al-0.6% Zr-0.4% Fe-0.4% Si alloy obtained by a similar process, this effect was not observed [22].
According to EMC rod hardness data obtained during annealing (Figure 4a), hardening reaches the highest level at 450 • C annealing stage temperature (the R450 state). Further increase in the annealing temperature leads to a significant decrease in HV, which is mainly due to the coarsening of the Al 3 Zr precipitates [5][6][7][8][9][10][11]16]. Deformation hardening was retained upon strip annealing to 450 • C. At this temperature, the hardness of the EMC rod is the same as for the cold rolled strip (Figure 4a). Further increase in the annealing temperature leads to a significant softening due to the formation of a recrystallized structure. At the maximum annealing temperature used, 600 • C, they had approximately the same hardness (32-33 HV) due to the coarsening and transformation of the Al 3 Zr precipitates to the equilibrium D0 23 phase [6,15].
Decomposition of the aluminum solid solution with the formation of L12 (Al3Zr) nanoparticles during annealing promotes the increase in electrical conductivity (EC), as shown in Figure 4b. At the same time, the difference between the EC values for the EMC rod and for the 2 mm strip remains approximately the same at all annealing temperatures up to 500 °C inclusively (2.5-3.0 MS/m). At this temperature, the maximum EC for a 2 mm strip is reached, but it corresponds to the softening stage (Figure 4a). Considering the maximum hardness and high electrical conductivity in the cold rolled strip after annealing at 450 °C, we used the same heat treatment for the prepared wire.
TEM microstructure of the ACZ alloy was examined for cold rolled strip in the S350 °C (Figure 5a,b) and S450 °C (Figure 5c,d) states to confirm the main structure changes described. According to obtained data for the both states, the fine individual particles of  Table 2. Decomposition of the aluminum solid solution with the formation of L1 2 (Al 3 Zr) nanoparticles during annealing promotes the increase in electrical conductivity (EC), as shown in Figure 4b. At the same time, the difference between the EC values for the EMC rod and for the 2 mm strip remains approximately the same at all annealing temperatures up to 500 • C inclusively (2.5-3.0 MS/m). At this temperature, the maximum EC for a 2 mm strip is reached, but it corresponds to the softening stage (Figure 4a). Considering the maximum hardness and high electrical conductivity in the cold rolled strip after annealing at 450 • C, we used the same heat treatment for the prepared wire.
Metals 2021, 11, x FOR PEER REVIEW 7 of 14 the eutectic Ca-containing intermetallics (dark in appearance) with a less than 1 µm size can be detected at sub-grain boundaries confirming their high pinning ability. However, detailed analysis revealed very few subtle particles in the S350 °C state (Figure 5b) which can be attributed to the initial stage of L12-Al3Zr phase formation. This assumption meets well with the electrical conductivity data presented in Figure 4b. In contrast, for the S450 °C state an exceptionally high number density and uniform distribution of the L12-Al3Zr phase nanoparticles are detected (Figure 5d,e). The result obtained suggests almost complete decomposition of the aluminum solid solution which converges well with data on the maximum electrical conductivity (Figure 4b) and hardness of the EMC rod (Figure 4a).
TEM microstructure of the ACZ alloy was examined for cold rolled strip in the S350 • C (Figure 5a,b) and S450 • C (Figure 5c,d) states to confirm the main structure changes described. According to obtained data for the both states, the fine individual particles of the eutectic Ca-containing intermetallics (dark in appearance) with a less than 1 µm size can be detected at sub-grain boundaries confirming their high pinning ability. However, detailed analysis revealed very few subtle particles in the S350 • C state (Figure 5b) which can be attributed to the initial stage of L1 2 -Al 3 Zr phase formation. This assumption meets well with the electrical conductivity data presented in Figure 4b. In contrast, for the S450 • C state an exceptionally high number density and uniform distribution of the L1 2 -Al 3 Zr phase nanoparticles are detected (Figure 5d,e). The result obtained suggests almost complete decomposition of the aluminum solid solution which converges well with data on the maximum electrical conductivity (Figure 4b) and hardness of the EMC rod (Figure 4a).

Properties of Wire
Mechanical and electrical properties of the wire ACZ alloy in as-drawn and annealed states are given in Table 3. In the initial state, the alloy has a good combination of strength (UTS ~ 280 MPa and YS ~ 250 MPa) and ductility (El ~ 4%), however, the electrical conductivity is small (~43% IACS). Annealing of the 3 mm wire according to the modes given in Table 2 allows one to increase the EC value significantly. In this case, the EC values are approximately the same as for the cold rolled strip (Figure 4b). This suggests that the decomposition of (Al) proceeds in a similar way. As can be seen from Table 3, the experimental alloy in the W450 state has the best combination of strength (UTS ~ 200 MPa and YS ~ 180 MPa), elongation (El ~ 12%) and electrical conductivity (54.7% IACS). Fractography of wire samples after a tensile test revealed a fine-dimpled ductile structure of the fracture surface ( Figure 6). Calcium-bearing particles found inside the

Properties of Wire
Mechanical and electrical properties of the wire ACZ alloy in as-drawn and annealed states are given in Table 3. In the initial state, the alloy has a good combination of strength (UTS~280 MPa and YS~250 MPa) and ductility (El~4%), however, the electrical conductivity is small (~43% IACS). Annealing of the 3 mm wire according to the modes given in Table 2 allows one to increase the EC value significantly. In this case, the EC values are approximately the same as for the cold rolled strip (Figure 4b). This suggests that the decomposition of (Al) proceeds in a similar way. As can be seen from Table 3, the experimental alloy in the W450 state has the best combination of strength (UTS~200 MPa and YS~180 MPa), elongation (El~12%) and electrical conductivity (54.7% IACS).
Fractography of wire samples after a tensile test revealed a fine-dimpled ductile structure of the fracture surface ( Figure 6). Calcium-bearing particles found inside the dimples (Figure 6a,b, BSE mode) are much smaller than the average diameter of the dimples. It should also be noted that no oxides or nonmetallic inclusions were observed which meets well with a previous study [22] confirming melt refining tendency when using EMC technology. dimples (Figure 6a,b, BSE mode) are much smaller than the average diameter of the dimples. It should also be noted that no oxides or nonmetallic inclusions were observed which meets well with a previous study [22] confirming melt refining tendency when using EMC technology.

Discussion
When comparing the basic characteristics of the new ACZ alloy and the previously studied Al-0.6% Zr-0.4% Fe-0.4% Si alloy [22] obtained under the same conditions, it can be seen that at close values of strength and electrical conductivity, the heat resistance of the Ca-containing alloy is significantly higher (450 vs. 400 °C) despite a smaller content of Zr (0.5 vs. 0.6 wt.%). Indeed, the hardness of the Ca-free alloy decreases down to 40 HV after annealing at 450 °C, which is significantly lower than that for the new alloy with calcium (Table 3). Obviously, the reason for the increase in the heat resistance is that the ACZ alloy contains calcium. Therefore, study of the effect of this element deserves special consideration. Considering that zirconium forms only the Al3Zr phase (stable and metastable modifications), to understand the distribution of calcium, iron and silicon between phases, it is necessary to consider the Al-Ca-Fe-Si system. Earlier [26], the structure of this phase diagram in the range of Al-Ca alloys (concentration of Ca much higher than Fe and Si) was reviewed but other fields (with small Ca content) were not studied. Using the calculation in the Thermo-Calc software [31], as well as the results of previously published works [22,[24][25][26]30,32] and additional experiments, we proposed structures of the Al-Ca-Fe-Si system in the aluminum corner including distribution of phases in the solid state

Discussion
When comparing the basic characteristics of the new ACZ alloy and the previously studied Al-0.6% Zr-0.4% Fe-0.4% Si alloy [22] obtained under the same conditions, it can be seen that at close values of strength and electrical conductivity, the heat resistance of the Ca-containing alloy is significantly higher (450 vs. 400 • C) despite a smaller content of Zr (0.5 vs. 0.6 wt.%). Indeed, the hardness of the Ca-free alloy decreases down to 40 HV after annealing at 450 • C, which is significantly lower than that for the new alloy with calcium (Table 3). Obviously, the reason for the increase in the heat resistance is that the ACZ alloy contains calcium. Therefore, study of the effect of this element deserves special consideration. Considering that zirconium forms only the Al 3 Zr phase (stable and metastable modifications), to understand the distribution of calcium, iron and silicon between phases, it is necessary to consider the Al-Ca-Fe-Si system. Earlier [26], the structure of this phase diagram in the range of Al-Ca alloys (concentration of Ca much higher than Fe and Si) was reviewed but other fields (with small Ca content) were not studied. Using the calculation in the Thermo-Calc software [31], as well as the results of previously published works [22,[24][25][26]30,32] and additional experiments, we proposed structures of the Al-Ca-Fe-Si system in the aluminum corner including distribution of phases in the solid state ( Figure 7a) and polythermal projection (Figure 7b). According to the proposed version, this system contains five four-phase regions: I-(Al) + Al 4 Ca + Al 10 CaFe 2 + Al 2 CaSi 2 , II-(Al) + Al 10 CaFe 2 + Al 2 CaSi 2 + Al 3 Fe, III-(Al) + Al 2 CaSi 2 + Al 3 Fe + Al 8 Fe 2 Si, IV-(Al) + Al 2 CaSi 2 + Al 8 Fe 2 Si + Al 5 FeSi, V-(Al) + Al 2 CaSi 2 + Al 5 FeSi + (Si). From the distribution shown in Figure 7a it follows that the Al 2 CaSi 2 phase is present in all regions of this quaternary system. Considering the low solubility of Ca in (Al), this means that even at a small amount of calcium in Fe and Si containing alloys, the formation of this particular ternary compound is inevitable. Excess calcium should lead to the formation of the Al 4 Ca and Al 10 CaFe 2 phases. The influence of calcium on the equilibrium phase composition of the Al-0.5% Fe-0.25% Si alloy (i.e., with the same concentrations as in the ACZ alloy) is reflected in Table 4. The calculation results show that the phase composition of the base ternary alloy has a very high sensitivity to the calcium content. In this case, the ACZ alloy must certainly be in region I. However, for nonequilibrium solidification, the phase composition can differ greatly from the equilibrium one. This is largely due to the occurrence of incomplete peritectic reactions. As follows from the polythermal projection (Figure 7b), there are three invariant peritectic and three eutectic reactions in the aluminum corner of the Al-Ca-Fe-Si system. The compositions of the liquid phase and the temperatures of these reactions are given in Table 5.
( Figure 7a) and polythermal projection (Figure 7b). According to the proposed version, this system contains five four-phase regions: I-(Al) + Al4Ca + Al10CaFe2 + Al2CaSi2, II-(Al) + Al10CaFe2 + Al2CaSi2 + Al3Fe, III-(Al) + Al2CaSi2 + Al3Fe + Al8Fe2Si, IV-(Al) + Al2CaSi2 + Al8Fe2Si + Al5FeSi, V-(Al) + Al2CaSi2 + Al5FeSi + (Si). From the distribution shown in Figure 7a it follows that the Al2CaSi2 phase is present in all regions of this quaternary system. Considering the low solubility of Ca in (Al), this means that even at a small amount of calcium in Fe and Si containing alloys, the formation of this particular ternary compound is inevitable. Excess calcium should lead to the formation of the Al4Ca and Al10CaFe2 phases. The influence of calcium on the equilibrium phase composition of the Al-0.5% Fe-0.25% Si alloy (i.e., with the same concentrations as in the ACZ alloy) is reflected in Table 4. The calculation results show that the phase composition of the base ternary alloy has a very high sensitivity to the calcium content. In this case, the ACZ alloy must certainly be in region I. However, for non-equilibrium solidification, the phase composition can differ greatly from the equilibrium one. This is largely due to the occurrence of incomplete peritectic reactions. As follows from the polythermal projection (Figure 7b), there are three invariant peritectic and three eutectic reactions in the aluminum corner of the Al-Ca-Fe-Si system. The compositions of the liquid phase and the temperatures of these reactions are given in Table 5.   As follows from the polythermal projection (Figure 7b), in a quaternary alloy containing 0.8% Ca, 0.5% Fe and 0.25% Si (point 1 in Figure 7b), after primary crystallization of (Al), eutectic reactions L→(Al)+Al 3 Fe and L→(Al) + Al 3 Fe + Al 2 CaSi 2 (line E 3 -P 1 ), and then peritectic L + Al 3 Fe→(Al) + Al 10 CaFe 2 + Al 2 CaSi 2 (point P 1 ) one should proceed. The incompleteness of the latter explains the presence of needle-like particles in the microstructure of the slowly solidified ACZ alloy (Figure 2d). With an increase in the cooling rate, the phase boundaries shift towards higher iron content (dashed line in Figure 7b), therefore the Al 3 Fe phase is not formed and it is absent in the as-cast microstructure of the EMC rod (Figure 2a,b). The solidification of this quaternary alloy (and hence the ACZ alloy) should end via eutectic reactions with the formation of three Ca-containing phases (point P 1 ). To further confirm the proposed structure of the Al-Ca-Fe-Si system, several quaternary alloys were annealed at 600 • C. As can be seen from Figure  To confirm the effect of cold deformation on the electrical conductivity of the ACZ alloy mentioned above, additional studies on the effect of calcium on EC of both as-cast ingots and cold rolled sheets containing 0.5% Fe and 0.25% Si at varying calcium concentrations (Table 1) were carried out ( Figure 9). As can be seen from Figure 9, the difference between the ingot and cold rolled sheet is small at small Ca content but at 0.75-1% Ca it reaches 2 MS/m, i.e., similar to the ACZ alloy (Figure 4b). Taking into account the low solubility of Ca in (Al) and the invariability of the phase composition during deformation, this effect can probably be caused by the influence of the dislocation structure, vacancies and other defects of the crystal structure. This requires special study. A slight increase in EC should be noted with the addition of 0.1% Ca to the ternary alloy. This can be explained by a decrease in the concentration of Si in (Al) due to the formation of Al 2 CaSi 2 compound. . Figure 9. Electrical conductivity of Al-Ca-Fe-Si alloys containing 0.5% Fe and 0.25% Si vs. calcium content curves: R-EMC rod, S-cold rolled strip. . Figure 9. Electrical conductivity of Al-Ca-Fe-Si alloys containing 0.5% Fe and 0.25% Si vs. calcium content curves: R-EMC rod, S-cold rolled strip.

1.
Experimental aluminum alloy containing 0.8% Ca, 0.5% Zr, 0.5% Fe and 0.25% Si (wt.%) in the form of a long-length rod 12 mm in diameter and ≈20 m in length was manufactured using an electromagnetic casting (EMC) technique. The extremely high cooling rate during alloy solidification (≈10 4 K/s) caused the formation of a favorable microstructure containing fine eutectic particles and full dissolution of Zr in Al solid solution. Due to the microstructure formed, the ingots possess high manufacturability for both cold drawing of a wire 3 mm in diameter and cold rolling of a strip in 2 mm in thickness.

2.
EMC rod hardness reaches the highest value at 450 • C annealing temperature which is associated with the formation of the L1 2 type Al 3 Zr phase precipitates with an average diameter of 10-20 nm and a high number density. Decomposition of aluminum solid solution during annealing also promotes the increase in the electrical conductivity (EC). Further increase in the annealing temperature leads to significant softening due to the coarsening of the Al 3 Zr precipitation structure. Deformation hardening in the cold rolled strip can be maintained at up to 450 • C annealing, which is associated with the high pinning ability of zirconium and calcium containing phases: Al 4 Ca, Al 10 CaFe 2 and Al 2 CaSi 2 . Further increase in the annealing temperature leads to softening due to the recrystallization. The best combination of hardness and EC in the cold rolled strip was reached after annealing at 450 • C.

3.
The general structure of Al-Ca-Fe-Si system in the Al corner (including distribution of phases in the solid state and polythermal projection) was proposed. 4.
The experimental wire alloy had the best combination of strength (UTS = 200 MPa, YS = 180 MPa), electrical conductivity (54.8% IACS) and thermal stability (up to 450 • C) as compared with alloys on the basis of Al-Zr and Al-REM systems.

5.
It was shown that the presence of calcium in the model alloy increases the electrical conductivity after cold forming operations (both drawing and rolling).