The aim of this work is to create a comprehensive database relating to mechanical properties (elastic limit, ultimate limit, and percentage elongation at the fracture) of Al-Si-Cu alloys (A319.2, B319.1, and A380). First of all, this involves specifying the effect of the iron content as well as evaluating the influence of the addition of modifying/neutralizing elements such as Sr, Be, Mn, Be + Sr, and Mn + Cr on the type 319 and 380 alloys having undergone T6 heat treatment. The second part, which relates to the eutectic alloy, studies the dissolution of the phase β-Al5FeSi by evaluating the effect of the iron content, the influence of modification by Sr. The last step is to establish a link between the tensile properties obtained and the characteristics of the microstructures, i.e., the percentage of porosities and the length and thickness of the platelets/pads. In total, 68 different compositions were prepared with an average number of 6–8 test pieces/composition. Also, the mode of rupture was studied using the scanning electron microprobe. The results show that strontium (Sr), manganese (Mn), and beryllium (Be) make it possible to partially neutralize the harmful effects of iron. The Sr fragments the phase (β-Al5FeSi then that Mn transforms the platelets into Chinese script). In addition, an Al12Mn phase may precipitate within the α-Al (i.e., pre-dendritic phase). As for beryllium, it is effective in both refining the β-phase and transforming it into a new phase of type BeSiFe2Al8. A sum of 700 tensile bars were tested.

The aim of this research is to study the effect of certain metallurgical parameters such as the addition of a mixture of rare earths (mischmetal) and superheating on the microstructure and tensile properties of the Al-Si-Cu alloy A319.2 containing 0.4%, 0.8% and 1.2% iron used in the automotive industry. The mischmetal (MM) precipitates in the form of platelets like the (3-Al5FeSi leading to a marked refinement in eutectic Si particles at 5% MM. In addition, alpha- Al15(Fe,Mn)3Si2. segregated particles and mischmetal-bound intermetallics persist in the microstructure even after T6 heat treatment. The tensile properties of 0.8% iron alloys deteriorate when the mischmetal concentration and superheat temperature increase, although the silicon phase undergoes significant changes. Alloys with a high iron concentration (1.2% Fe) showed a slight decrease in the length of the (3-Al5FeSi phase platelets and of the mischmetal compared to alloys with 0.4% and 0.8% Fe when the concentration of mischmetal increases to 5% and when the superheating temperature reaches 950 degrees C. This observation explains the increase in the % elongation to fracture of the 1.2% Fe-5% mischmetal alloy cast directly from 750 degrees C or after superheating at 950 degrees C, followed by in-furnace cooling to 750 degrees C. The ultimate tensile strength and yield strength degrade with mischmetal, but improve slightly with superheating; only for the 1.2% Fe-0% mischmetal alloy, its yield strength decreases once superheated to 950 degrees C.

The aim of this work is to create a comprehensive database relating to the tensile properties of a eutectic Al-Si-Mg alloy. The studies reported herein cover the dissolution of the (3-iron Al5FeSi phase by evaluating the effect of the iron (Fe) content, the influence of modification by strontium (Sr), and the duration of the solutionizing treatment from 0 to 200 hat 540 degrees C. The last step is to establish a link between the tensile properties obtained and the characteristics of the microstructures, mainly the length of the (3-Al5FeSi platelets. Solution treatment at 540 degrees C was applied to the eutectic alloys for times of up to 200 h. Unmodified and modified Al-Si-Mg alloys with high Fe content accelerate the dissolution of (3-Al5FeSi; this being due to the rejection of silicon (Si) atoms towards aluminum (Al) and resulting in transforming the (3-Al5FeSi into Al6Fe. The unmodified alloy shows a maximum reduction in the length of the (3-phase platelets after 30 h of solution treatment, compared to 10 h for the modified alloy. Therefore, Sr addition decreases the duration of treatment due to the initial fragmentation of platelets. The process of fragmentation/dissolution of the (3-Al5FeSi phase during solution treatment at 540 degrees C is associated with the ductile Al matrix characterized by the formation of dimple structure. The lack of an age hardening response of the ternary Al-12%Si-0.045%Sr alloy results in low alloy strength, making this alloy unsuitable for automotive components that may be exposed to high temperatures. The results of this study were supported by extensive tensile testing (about 1000 tensile bars). The quality-index method was found to be useful in classifying the alloys according to their performance.

The A413.1 aluminum alloy is known for its excellent fluidity, corrosion resistance and good mechanical properties which make it an ideal candidate for complex shapes and thin-walled castings. This alloy is commonly used in automotive components, housings and general industrial applications. The microstructure of A413.1 alloys comprises several intermetallic phases; however, only the β-Al5FeSi phase influences the size of the eutectic silicon particles. These compounds solidify first and carry with them a certain quantity of strontium which remains near these compounds to more significantly modify the surrounding eutectic silicon particles. The other intermetallic phases do not affect the morphology of the eutectic silicon particles. The addition of strontium only and strontium together with magnesium improves the ultimate strength of as-cast alloys while the addition of silver and zinc improves the yield strength. After a T4 heat treatment, it is the base alloy—with an addition of strontium and copper—that obtains the highest tensile strength values. Dissolving for twenty-four hours does not improve the strength of the alloys compared to dissolving for four hours. For T6 heat treatments, aging at 155 °C is more appropriate for alloys not containing copper, and aging at 180 °C increases the properties of alloys which do contain it. On the other hand, the aging temperature of 240 °C is too high to be applied for five hours as it produces overaging. Aging at a temperature of 180 °C considerably reduces the ductility of the alloys. In this case, many of the tensile bars are fractured in the elastic region. The study was supported by the use of quality index charts. About 1200 tensile test bars were pulled to fracture during the course of these investigations.

Nine different compositions of were studied: the basic 413.1 alloy and this same alloy with different additions of strontium (Sr), magnesium (Mg), copper (Cu), silver (Ag), lanthanum (La), cerium (Ce), zinc (Zn) and nickel (Ni). The present study makes it possible to draw conclusions concerning the modifications of the microstructure and the variations of mechanical properties in traction depending on the composition of the alloys and the heat treatments applied. The result is put into solution at 495 °C for two different periods of 4 or 24 h. Four types of quenching are used: cooling in ambient air, quenching in hot water (60 °C) and two quenches in a device projecting water and air under pressure. The two temperatures of the water used at the inlet of this device are 12 °C and 55 °C. This type of quenching produces intermediate cooling between ambient air cooling and hot water quenching. The addition of strontium and magnesium improves the ultimate strength of as-cast alloys, while the addition of silver and zinc improves the yield strength. After a T4 heat treatment, it is the base alloy with an addition of strontium and copper which obtains the highest tensile strength values. Dissolving for 24 h does not improve the strength of the alloys compared to dissolving for 4 h. The conclusions of this study are that increasing the solution time increases the changes produced on the morphology of the eutectic Si particles. The intermetallic phases which dissolve do so after 4 h of being in solution at 495 °C. The intermetallic phases Q-Al5Cu2Mg8Si6 as well as those containing iron, nickel or rare earth metals did not dissolve after 24 h of solutionizing treatment.

The present study was undertaken to elaborate on the parameters controlling the microstructural characterization of A319.2 Al–Si alloys, as a function of iron content (0.12–0.8

The current study is aimed to enhance the tensile performance of Al–Si–Cu–Mg cast alloys at both ambient and elevated temperatures. The investigation is focused on incorporating zirconium (Zr) as a primary alloying element, alongside nickel (Ni) and manganese (Mn), to assess their suitability for automotive engine applications. In Mn-containing alloys, tensile strength improvement was observed due to the precipitation of compacted α-Al15(Fe, Mn)3Si2 and Al6Mn phases. Meanwhile, Ni-bearing phases such as Al3CuNi and Al3Ni in Ni-containing alloys were found to inhibit crack propagation, thereby enhancing tensile properties. Results indicated that the addition of 0.75 wt.

The present work was performed on experimental Al–Si near eutectic cast alloys, with different additives mainly Fe, Mg, Mn, Cr, Sr and P. The alloys were solidified at 0.8°C/s, very close to equilibrium conditions. Precipitated phases, primarily Fe-, Cu-, Mg-, and Sr-based intermetallics, were examined. Although the phases reported in the present work were documented previously, the range of chemical composition of each phase was confirmed using an electron probe microanalyzer (EPMA) equipped with wavelength dispersive spectroscopy (WDS) and electron dispersive X-ray spectroscopy (EDS) facilities. Some of these alloys were cast in the form of hardness test pieces using a steel permanent mold preheated at 425 °C that provided a microstructure with an average dendrite arm spacing (DAS) of 22 µm. The test pieces were solution heat treated at 500 ± 2 °C for times up to 24 h, followed by artificial aging at 155 °C for 5 h (T6 treatment). Hardness tests were carried out on the heat-treated test pieces. It was found that addition of Sr decreased the hardness. The role of P addition (AlP) on the nucleation of primary Si particles has been discussed. Although the addition of P in terms of 30 ppm leads to refining of the primary Si particles, the P-Sr interaction has a marked negative effect of the modification of the eutectic Si particles.

The melts of the studied alloys were poured into a preheated (450 °C) L-shaped rectangular mold. Samples sectioned from the castings were solution heat-treated at 495 °C for 8 h, then quenched in warm water at 65 °C, followed by artificial aging at 155°, 180°, 200°, 220°, and 240 °C, respectively, for 5 h (i.e., T6 and T7-tempered). The hardness measurements were carried out using a Brinell hardness tester. Multiple regression models were developed in order to predict the influence of compositional variations on the hardness of T6-aged 396 alloy. The results show that increasing the content of Cu, Mn, and Mg results in an increase in hardness. Copper results in the highest contribution of hardness for the composition range studied, while Fe has deleterious effects on the hardness properties of the alloy. Detailed analysis indicates that the interaction of coefficients does not appear to contribute significantly to the mechanical properties of the alloys. It may also be observed that the hardness of as-cast and heat-treated B319.2 and A356.2 alloys is reduced slightly by Sn, due to precipitation of soft tin-particles.

The purpose of this study is to investigate the potential of zirconium (Zr) and nickel (Ni) in enhancing the strength of 319-type cast alloys at high temperature. The high-temperature testing was performed on tensile bars either in the as cast or T6 tempered (190 °C/2h) condition. High-temperature tensile tests were performed at 25, 190, 250 and 300 °C. Tensile bars were held at each temperature for 10h prior to pulling to fracture. The results revealed that (Al,Si)3(Zr,Ti), Al3CuNi, Al65Si16Ni13 or Al4SiNi and Al9NiFe phases are the main features in the microstructures of alloys containing Zr and Ni. In addition, other phases containing Cu such as Al5Fe2Cu2, AlSiFeNiZrCu (probably Al4SiNi (Cu, Fe, Zr) or Al4SiNi with traces of Cu, Fe, Zr), and Q-Al5Cu2Mg8Si6 could also be formed. All these phases result in depletion in the Cu content and hence reduction in the alloy strength. Both Al2Cu and Al3Zr are the hardening phases during artificial aging. The tensile properties were plotted as a function of aging temperature and in the form of Q-charts. The fracture behavior of selected samples was examined as well, using FESEM microscopy.

The present work was performed on experimental Al-Si near eutectic cast alloys, with different additives, mainly Fe, Mg, Mn, Cr, Sr and P. The alloys were solidified at 0.8°C/s, very close to equilibrium conditions. Precipitated phases, primarily Fe-, Cu-, Mg-, and Sr-based intermetallics, were examined. Although the phases reported in the present work were documented previously, the range of chemical composition of each phase was confirmed using an electron probe microanalyzer (EPMA) equipped with wavelength dispersive spectroscopy (WDS) and electron dispersive X-ray spectroscopy (EDS) facilities. Some of these alloys were cast to produce hardness test samples using a metallic permanent mold preheated at 425 °C that provided a microstructure with an average dendrite arm spacing (DAS) of 22 µm. Samples were solution heat treated at 495 °C ± 2 °C for times up to 24 h, followed by quenching in warm water (65 °C), and thereafter artificial aging at 155 °C for 5 h (T6 treatment). Hardness and impact tests were carried out on the heat-treated test bars.

The present study aimed at investigating the influence of grain refinement in combination with Sr modification on the solidification behaviour of A356.2 alloy, and the resulting micro- and macrostructures obtained. Grain refinement of A356.2 alloy using Ti and B additions in the ranges of 0.02- 0.5% and 0.01-0.5% respectively was studied using five different grain refiners in the form of Al-10% Ti, Al-5%Ti-1% B, Al-2.5% Ti-2.5% B, Al-1.7% Ti-1.4%% B and Al-4% B aluminium master alloys. Sr modification of the alloys was carried out using Sr additions of 30 and 200 ppm in the form of Al-10% Sr master alloy. The probable interactions between Sr and Ti and Sr and B were investigated using different metallographic techniques. Thermal analysis was also used to evaluate these interactions. Electron microprobe analysis revealed that adding>0.1% B to the A356.2 alloy may lead to formation of particles predominantly containing B and Sr, with a composition approaching SrB6.

The present work was performed on experimental Al-Si near eutectic cast alloys, with different additives mainly Fe, Mg, Mn, Cr, Sr and P. The alloys were cooled at 0.8 degrees C s(-1), very close to equilibrium conditions. Precipitated phases, primarily Fe, Cu, Mg and Sr based intermetallics, were examined. Although the phases reported in the present work were documented previously, the range of chemical composition of each phase was confirmed using an electron probe microanalyser equipped with wavelength dispersive spectroscopy and electron dispersive X-ray spectroscopy facilities.

The present study aims to investigate the influence of the addition of Ti and B in the form of five different grain refiners/aluminium master alloys (Al–10%Ti, Al–5%Ti–1%B, Al–2.5%Ti–2.5%B, Al–1.7%Ti–1.4%B and Al–4%B) in conjunction with that of Sr (as modifier) added in the form of Al–10%Sr master alloy to A356.2 alloy. Grain refinement of an A356.2 alloy with Ti and B additions in the ranges of 0.02–0.5% and 0.01–0.5%, respectively, was examined using these different types of grain refiners. Strontium additions of 30 and 200 ppm were made. All alloys were T6-heat treated before mechanical testing. Tensile and impact tests were conducted to evaluate the influence of the interaction between grain refiner and modifier on the mechanical properties. The properties were determined for both the as-cast and heat-treated conditions.

Fracture behavior, as well as impact toughness, is influenced by alloy composition, solidification rate, and the heat treatment conditions applied. This study was undertaken to investigate the effects of intermetallics on the fracture behavior of non-modified and Sr-modified Al-Si-Cu-Mg base alloys. Castings were prepared from both experimental and industrial 319 alloy melts containing 0-0.6wt% Mg. Test bars were cast in two different molds, namely a star-like permanent mold and an L-shaped permanent mold, which provided cooling rates corresponding to secondary dendrite arm spacing (SDAS) values of 24 and 50 mu m (0.00095 and 0.00197 in.), respectively. The bars were tempered at 180C (356F) (T6 treatment) and 220C (428F) (T7 treatment) for 2-48 hours. It was observed that the addition of Mg resulted in the precipitation of the beta-Mg2Si, Q-Al5Mg8Cu2Si6, pi-Al8Mg3FeSi6, and the blocklike theta-Al2Cu phases. The fractured surfaces of non-modified alloys exhibited long Si particles with cracks in the interior, while those of the Sr-modified alloys displayed a dimpled structure throughout the matrix. Increasing the Mg content up to 0.6% resulted in the appearance of fractured particles of Q-Al5Mg8Cu2Si6 and pi-Al8Mg3FeSi6 phases. Decreasing the cooling rate or increasing the aging temperature did not alter the fracture mechanism with respect to the alloy composition.

This paper investigates the effect of alloying elements, namely, Sn, Fe, and Mn, and drilling tool materials with a standard geometry on the machinability of heat-treated hypoeutectic. B319.2 and near-eutectic 396 alloys. The results reveal that the 396 alloy displays the most rapid increase in the total drilling force and moment with an increase in the number of holes drilled. The differences in machining behavior of the 396 and B319.2 alloys may be attributed mainly to the variation in the silicon content, 10.8%Si and 7.5%Si, respectively. The addition of 0.15% Sn to the 396 and B319.2 alloys has a beneficial effect on the tool life of the different drills used. The presence of sludge in the 396 alloy resulting from the addition of 0.25%Fe and 0.25%Mn, leads to an extremely rapid increase in the total drilling force and moment and has an unfavourable effect on tool life. A visual examination of the chips reveals that the fan shape is by far the predominant form during the drilling of the alloys studied. Also, the fan shape, due to its compact size and shape, is the ideal chip for most drilling applications.

Critical automotive applications using heat-treatable alloys are designed for high values of mechanical properties, which can be improved using a specified heat treatment. Castings were prepared from both experimental and industrial 319 alloy melts containing 0 to 0.6wt% Mg. Impact test bars were cast in two different cooling rate molds, namely a star-like permanent mold and an L-shaped permanent mold, with DASs of 24 mu m and 50 mu m, respectively. Tensile test bars were cast in an ASTM B108 permanent mold with a DAS of 25 mu m. The bars were tempered at 180C (356F) and 220C (428F) for 2-48 h. The results showed that Mg content, aging conditions and cooling rate have a significant effect on the microstructure of both experimental and industrial alloys and, consequently, on the mechanical properties. The addition of Mg resulted in the precipitation of the beta-Mg2Si, Q-Al5Mg8Cu2Si6, pi-Al8Mg3FeSi6 and of the block-like theta-Al2Cu phases. The presence of Mg and Cu, as well as the higher cooling rates improved the alloy strength, ductility and hardness values, especially. in the T6 heat-treated condition. As a result of this treatment, the alloys show hardening after up to 24 h of aging time because of the influence of several hardening phases. The activity of Cu significantly lowers the impact properties, which are determined mainly by the Al2Cu phase and not by the eutectic Si particles. The addition of Mg was also seen to diminish the effects of impact toughness. The crack initiation energy in these alloys is greater than the crack propagation energy, reflecting the high ductility of Al-Si-Cu-Mg base alloys. Applying aging at 220C, (428F) causes overaging and alloy softening after 2 h of aging time. The experimental alloys demonstrate higher values of mechanical properties than the industrial alloys.

Castings were prepared from both experimental and industrial 319 alloy melts containing 0-0.6 wt% Mg. Test bars were cast in two different cooling rate molds, a star-like permanent mold and an L-shaped permanent mold, with DASs of 24 mu m and 50 mu m, respectively. The bars were tempered at 180 degrees C (T6 treatment) and 220 degrees C (T7 treatment) for 2-48 h. The results showed that Mg content, aging conditions, and cooling rate have a significant effect on the microstructure of both experimental and industrial alloys and, consequently, on the hardness. The addition of Mg resulted in the precipitation of the beta-Mg2Si, Q-AL(5)Mg(8-)Cu(2)Si(6), pi-Al8Mg3FeSi6 and of the block-like 0-Al2Cu phases. The Mg and Cu, as well as the higher cooling rates improved the hardness values, especially in the T6 heat-treated condition, whereas the addition of Sr decreased these values. (C) 2010 Elsevier Ltd. All rights reserved.

Critical automotive applications using heat-treatable alloys are designed for high impact toughness which can be improved using a specified heat treatment. The alloy toughness and fracture behavior are influenced by the alloy composition and the solidification conditions applied. The mechanical properties of alloys containing Cu and Mg can also be enhanced through heat treatment. The present study was undertaken to investigate the effects of Mg content, aging and cooling rate on the impact toughness and fractography of both non-modified and Sr-modified Al-Si-Cu-Mg base alloys. Castings were prepared from both experimental and industrial 319 alloy melts containing 0-0.6wt% Mg. Test bars were cast in two different cooling rate molds, a star-like permanent mold and an L-shaped permanent mold, with dendrite arm spacing (DAS) values of 24 and 50 mu m, respectively. Test bars were aged at 180 degrees C and 220 degrees C for 2-48 h. Charpy Impact test was used to provide the impact energy. It was observed that high cooling rates improve the impact toughness whereas the presence of Cu significantly lowers the impact properties which are determined mainly by the Al(2)Cu phase and not by the eutectic Si particles. The addition of Mg and Sr were also seen to decrease the impact toughness. The crack initiation energy in these alloys is greater than the crack propagation energy, reflecting the high ductility of Al-Si-Cu-Mg base alloys. (C) 2011 Elsevier Ltd. All rights reserved.

This study investigated the effects of cooling rate, heat treatment as well as additions of Mn and Sr on hardness and hardening characteristics in Al–11Si–2.5Cu–Mg alloys. The results of scanning electron microscopy reveal that the age-hardening behaviour is related to the precipitation sequence of alloy. An energy dispersive spectroscopy analysis was used to identify the precipitated phases. The results also show that the hardness of the solution heat-treated samples is higher in air-cooled alloys than in furnace-cooled ones. Furthermore, the hardness observed in solution heat-treated samples is higher than in as-cast samples for air-cooled alloys, with the highest hardness level in the non-modified alloys. The highest hardness levels among the artificially aged samples were observed in the non-modified, air-cooled alloys. These levels occur after aging for longer times at lower temperatures (e.g. 30h at 155°C). The alloys studied did not display any softening after 44h at 155°C, whereas at 180°C, softening was noted to occur after 10–15h. At short aging times of 5–10h, high hardness values may be obtained by aging at 180°C. At aging temperatures of 200°C, 220°C and 240°C, softening began after 2h had elapsed. The cooling rate during solidification does not appear to have any significant effect on the precipitation characteristics and hardness of the Sr-modified alloys at certain aging temperatures. On the other hand, the effects of cooling rate may be clearly observed in the non-modified alloys. Manganese has a minimal effect on the hardness of the aged samples as it diminishes the potential action of age-hardening, while strontium lessens the hardness of the artificially aged samples. The effect of strontium, however, is more pronounced in the air-cooled alloys than in the furnace-cooled alloys. Strontium also has a noticeable effect on the reduction of hardness in aged Mg-containing Al–Si–Cu alloys, in that it affects the precipitates containing Cu and Mg.