Commercial AlSi7Mg alloy represents the usual choice for complex geometry casting production. The market imperative to improve mechanical properties imposed the design of new chemical composition of ...AlSi7MgCu alloy with high content of Cu (up to 1.435 wt.%). This represents a challenge in order to achieve advanced properties. The interaction of a number of alloying (Si, Mg, Cu) and trace elements (Fe, Mn) influenced a wide range of complex reactions occurring and therefore leading to intermetallic phase precipitation. The characterization of novel chemical composition interaction and its solidification sequence was achieved by modelling an equilibrium phase diagram, simultaneously performing both thermal analysis and metallographic investigations. Copper influence was indicated in the whole solidification process starting with infiltration in modified Chinese script phase Al15(Fe,Mn,Cu)3Si2, beside common intermetallic Al5FeSi. Copper addition encourages formation of compact complex intermetallic phases Al5Cu2Mg8Si6 and Al8(Fe,Mn,Cu)Mg3Si6. Solidification ended with secondary eutectic αAl + Al2Cu + βSi. Microstructure investigation allows volume reconstruction of the microstructure and distribution of particular phases. Chemical compositions enriched in copper content and developed microstructural constituent through solidification sequence of AlSi7MgCu alloy contribute to a significant increase in mechanical properties already in an as-cast state.
Aluminium alloys possess excellent mechanical, physically chemical and technological properties which have found an extensive application in the automotive industry. Alloy AlSi11 belongs to a group ...of eutectic alloys characterized by high fluidity, low pouring temperature and narrow solidification interval which comprehend to the uniformly distributed eutectic microstructure indicating superior mechanical and technological properties. Study of AlSi11 alloy solidification sequence has been accompanied by calculation of equilibrium phase diagram, and simultaneous thermal analysis, all in correlation with microstructure development. Thermodynamic calculation revealed solidification sequence with corresponding temperatures in equilibrium state. Differential scanning calorimetry enables determination of exact temperatures of phases’ transformations correlated at different cooling rates. Dilatometer thermal analysis defined dimensional changes of AlSi11 alloy. Microstructural examination revealed development of following constituents: primary aluminium (α
Al
), high-temperature intermetallic phases on the iron base (Al
5
FeSi and/or Al
15
(Fe,Mn)
3
Si
2
), binary eutectic (α
Al
+ β
Si
) and secondary eutectic (Mg
2
Si and Al
5
Mg
8
FeSi
6
) as a last solidifying phases. Synergy of performed phase diagram calculation, thermodynamic and microstructural investigation enables determination of thermodynamic stability of AlSi11 alloy exposed to different cooling conditions, with respect to phase’s evolution.
The utilization of aluminum-lithium-magnesium (Al-Li-Mg) alloys in the transportation industry is enabled by excellent engineering properties. The mechanical properties and corrosion resistance are ...influenced by the microstructure development comprehending the solidification of coherent strengthening precipitates, precipitation of course and angular equilibrium phases as well as the formation and widening of the Precipitate-free zone. The research was performed to determine the microstructure degradation of Al-2.18Mg-1.92Li alloy in a corrosive environment using electrochemical measurements. The solidification sequence of the Al-2.18Mg-1.92Li alloy, obtained using Thermo–Calc software support, indicated the transformation of the αAl dendritic network and precipitation of AlLi (δ), Al2LiMg (T), and Al8Mg5 (β) phase. All of the phases are anodic with respect to the αAl enabling microstructure degradation. To achieve higher microstructure stability, the sample was solution hardened at 520 °C. However, the sample in as-cast condition showed a lower corrosion potential (−749.84 mV) and corrosion rate (17.01 mm/year) with respect to the solution-hardened sample (−752.52 mV, 51.24 mm/year). Higher microstructure degradation of the solution-hardened sample is a consequence of δ phase precipitation at the grain boundaries and inside the grain of αAl, leading to intergranular corrosion and cavity formation. The δ phase precipitates from the Li and Mg enriched the αAl solid solution at the solution-hardening temperature.
This paper presents the results of an analysis of the formation of an intermetallic bond between a ring carrier and an aluminum piston alloy. The ring carrier is made of austenitic cast iron ...(Ni-Resist) to increase the wear resistance of the first ring groove and is applied in highly loaded diesel engines. The most important thing is that the Ni-Resist (ferrous) must be bonded with a non-ferrous piston material during the casting of the piston. A metallographic investigation using an optical microscope in combination with the SEM/EDS analysis of the quality of the intermetallic bonding layer was done. The test results show that if the proper conditions are met, then the preparation of the ring carrier can be made successfully, as can the formation of the metal connection between the two materials of different qualities.
The design of materials through the selection of the chemical composition, thermodynamic modelling, melt treatment by inoculation and modification, correctly developed casting technology followed by ...adequate heat treatment could improve casting properties. Due to castings complex geometry and customer properties, casting manufacturers are forced to adopt production process with additional steps such as heat treatment. Rigorous regime with relatively high temperature and long holding time indicates the microstructural changes in the material, thus indirectly affects the mechanical properties of the material. An important aspect for further improvement and application is to develop a better understanding of the microstructural constituent changes due to performed heat treatment and consequently improved mechanical properties. Heat treatment is accompanied with increased costs and longer time for total production, which cause lower competitiveness of casting producer per produced casting. Comparison of obtained properties in as-cast and heat-treated state reveals an evaluation of applied production procedures, closely connected with investments in money and time vs. obtained properties improvement. Conventional AlSi7Mg alloy represents a frequent selection for complex geometry castings production. Designing of new chemical composition of AlSi7Mg(Cu) alloy with extra addition of Cu (up to 1.435 wt.%) represents a challenge in order to achieve advanced mechanical properties already in as-cast state. A wide range of complex reactions and intermetallic phases occurs due to numerous alloying (Si, Mg, Cu) and trace elements (Fe, Mn) interaction. Performed heat treatment influences on iron bearing phases' morphology change, refining of microstructural constituents and enrichment of metal matrix on secondary alloying elements such as Cu and Mg. Exact determination of alloy behaviour was performed by modelling of equilibrium phase diagram, simultaneous thermal analysis and metallographic investigations in both states, as-cast and heat-treated, respectively. Heat- treated microstructure experiences the change like refining and uniform distribution of microconstituents, metal matrix enrichment on magnesium and copper, and therefore fragmentation of last solidifying phases'. Innovated chemical composition and determined solidification sequence of particular phases as well as theirs morphology and distribution comprehend to significant increase of tensile mechanical properties already in as-cast state. Heat treatment did not influenced on significant improve of mechanical properties.
Novel multicomponent AISi9MgMn alloy has been investigated due to unusual chemical composition. An AISi9MgMn alloy is the first aluminum alloy with low iron and intentionally high manganese content ...developed for structural automotive casting parts and sets produced by high pressure die casting process. This alloy has been characterised by enhanced mechanical properties of castings such as ductility and toughness at high cooling rates due to evolution of intermetallic Al^sub x^ Mn^sub y^ Fe^sub z^ Si^sub u^ phase in globular manner. Characterization of novel multicomponent AISi9MgMn alloy at high cooling rate related to high pressure die casting indicates evolution of fine intermetallic phases with globular morphology which directly influence on development of enhanced mechanical properties. Investigation revealed evolution of characteristic microstructural constituents on the base of their morphology and chemical composition: primary aluminum (α^sub Al^) with mixed dendrite and globular morphology, complex intermetallic phase Al^sub x^Mn^sub y^Fe^sub z^Si^sub u^ in globular / polyhedron morphology, main eutectic in interdendritic spaces (α^sub Al^+ β^sub Si^). Complex intermetallic phase Al^sub x^Mn^sub y^Fe^sub z^Si^sub u^ evaluated at high cooling rate reveals globular or polyhedron morphology which indicates independently evolution in early stages of solidification, due to both local undercooling and liquid composition which allow direct nucleation of the equilibrium phase in the liquid by individual nucleation and growth or by increase in thickness of that originated previously, that have been transported mainly by diffusion in the liquid. Eutectic posses mixed lamellar and fibrous morphology. Obtained mechanical properties were very high when compared to common aluminium automotive alloys. A significant differentiation has been established due to increasing of cooling / solidification rate obtained by several sample diameters. Test samples exposed to higher cooling rate due to their geometry (smaller diameter) show increase in yield and tensile strength and elongation due to finer microstructure, prominent globular microstructure of primary aluminium, intermetallic Al^sub x^Mn^sub y^Fe^sub z^Si^sub u^ phase and completely modified fibrous eutectic. Characterization of novel multicomponent AISi9MgMn alloy indicates applicability of this material for safety automotive parts due to obtained high values of mechanical properties.
Novel multicomponent AlSi9MgMn alloy has been investigated due to unusual chemical composition. An AlSi9MgMn alloy is the first aluminum alloy with low iron and intentionally high manganese content ...developed for structural automotive casting parts and sets produced by high pressure die casting process. This alloy has been characterised by enhanced mechanical properties of castings such as ductility and toughness at high cooling rates due to evolution of intermetallic Al sub(x) Mn sub(y) Fe sub(z) Si sub(u) phase in globular manner. Characterization of novel multicomponent AlSi9MgMn alloy at high cooling rate related to high pressure die casting indicates evolution of fine intermetallic phases with globular morphology which directly influence on development of enhanced mechanical properties. Investigation revealed evolution of characteristic microstructural constituents on the base of their morphology and chemical composition: primary aluminum ( alpha sub(Al)) with mixed dendrite and globular morphology, complex intermetallic phase Al sub(x)Mn sub(y) Fe sub(z)Si sub(u) in globular / polyhedron morphology, main eutectic in interdendritic spaces ( alpha sub(Al)+ beta sub(Si)). Complex intermetallic phase Al sub(x)Mn sub(y)Fe sub(z)Si sub(u) evaluated at high cooling rate reveals globular or polyhedron morphology which indicates independently evolution in early stages of solidification, due to both local undercooling and liquid composition which allow direct nucleation of the equilibrium phase in the liquid by individual nucleation and growth or by increase in thickness of that originated previously, that have been transported mainly by diffusion in the liquid. Eutectic posses mixed lamellar and fibrous morphology. Obtained mechanical properties were very high when compared to common aluminium automotive alloys. A significant differentiation has been established due to increasing of cooling / solidification rate obtained by several sample diameters. Test samples exposed to higher cooling rate due to their geometry (smaller diameter) show increase in yield and tensile strength and elongation due to finer microstructure, prominent globular microstructure of primary aluminium, intermetallic Al sub(x)Mn sub(y)Fe sub(z)Si sub(u) phase and completely modified fibrous eutectic. Characterization of novel multicomponent AlSi9MgMn alloy indicates applicability of this material for safety automotive parts due to obtained high values of mechanical properties.
The automotive industry is forced to apply advanced materials and technologies in order to overcome the mutual competition, but also for compliance with environmental regulations requiring reduction ...of emissions, and fuel consumption. One of main component for achieving this goal is weight saving by downsizing of components using advanced materials and production technologies. The widest production of automotive aluminium component refers to wheels produced by low pressure die casting. Complex geometry of thin wall wheel casting indicates application of AlSi11 alloy (EN AC 44000). An AlSi11 alloy (EN AC 44000) belongs to the group of "eutectic alloys" and is characterized with relatively low melting point and narrow solidification interval which both brought to the uniformly distributed eutectic microstructure indicating superior mechanical and technological properties. This is the reason for this alloy to be widely used for high and low pressure die casting production. Silicon is one of the most important alloying elements which comprehend to good castability of aluminium alloys. Addition of silicon improves resistance to hot cracks and feeding capability. Synergy of influenced alloying and trace elements effect comprehend to different intermetallic phase evolution. The content of secondary alloying elements (Mg, Cu) and trace elements (Fe, Mn, Cr, Zn) was minor in investigated AlSi11 alloy. Also thin wall casting geometry using low pressure die casting technology ensures rapid cooling with minimal available time for significant number of intermetallic phases development. Metallographic analysis resulted in following microstructural constituents: primary aluminium α^sub Al^, main eutectic α^sub Al^ + β^sub Si^, high temperature iron phase Al^sub 5^FeSi, intermetallic phases in form of secondary eutectic Mg^sub 2^Si and Al^sub 8^FeMg^sub 3^Si^sub 6^. Correlation of established microstructural constituents with thermodynamic modelling and differential scanning calorimetry indu :es exact solidification sequence for this particular chemical composition.
The automotive industry is forced to apply advanced materials and technologies in order to overcome the mutual competition, but also for compliance with environmental regulations requiring reduction ...of emissions, and fuel consumption. One of main component for achieving this goal is weight saving by downsizing of components using advanced materials and production technologies. The widest production of automotive aluminium component refers to wheels produced by low pressure die casting. Complex geometry of thin wall wheel casting indicates application of AlSi11 alloy (EN AC 44000). An AlSi11 alloy (EN AC 44000) belongs to the group of "eutectic alloys" and is characterized with relatively low melting point and narrow solidification interval which both brought to the uniformly distributed eutectic microstructure indicating superior mechanical and technological properties. This is the reason for this alloy to be widely used for high and low pressure die casting production. Silicon is one of the most important alloying elements which comprehend to good castability of aluminium alloys. Addition of silicon improves resistance to hot cracks and feeding capability. Synergy of influenced alloying and trace elements effect comprehend to different intermetallic phase evolution. The content of secondary alloying elements (Mg, Cu) and trace elements (Fe, Mn, Cr, Zn) was minor in investigated AlSi11 alloy. Also thin wall casting geometry using low pressure die casting technology ensures rapid cooling with minimal available time for significant number of intermetallic phases development. Metallographic analysis resulted in following microstructural constituents: primary aluminium alpha sub( Al), main eutectic alpha sub( Al) + beta sub( Si), high temperature iron phase Al sub( 5)FeSi, intermetallic phases in form of secondary eutectic Mg sub( 2)Si and Al sub( 8)FeMg sub( 3)Si sub( 6). Correlation of established microstructural constituents with thermodynamic modelling and differential scanning calorimetry indu :es exact solidification sequence for this particular chemical composition.
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