The Solidification Path of the Complex Metallic Al-Mn-Be Alloy

The solidification paths of the Al86.1Mn2.5Be11.4 and Al84Mn5.1Be10.9 alloys, melt spun, cast into a copper mould and controlled cooled (during DSC) were investigated by means of light-optical microscopy (LOM), differential scanning calorimetry (DSC) combined with thermogravimetry (TG) or simultaneous thermal analysis (STA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Auger electron spectroscopy (AES) and the X-ray diffraction (XRD) line in Elletra Trieste, Italy. The constitutions of samples from both alloys were examined in all three states, i.e., after melt spinning, after casting into a copper mould and after differential scanning calorimetry. It was established that in the cast and controlled-cooled specimens the alloys consisted of an aluminium-rich αAl-matrix, and the Al4Mn and Be4AlMn phases. In the case of casting and DSC the primary crystallization began with the precipitation of the Be4AlMn phase, followed by what can most likely be characterized as a uni-variant binary eutectic reaction L → (Be4AlMn + Al4Mn). The solidification process continued with an invariant ternary eutectic reaction, where the remaining melt (L) formed the heterogeneous structure (αAl + Al4Mn + Be4AlMn) or a ternary eutectic. When extremely high cooling rates were employed, as is the case with melt-spinning, the constituting phases of both alloys were precipitated in a very small form and the Be4AlMn phase was completely absent in the form of primary polygonal particles and replaced by the icosahedral quasicrystalline phase or the i-phase. There was also no evidence of the Al4Mn phase. The distribution, size and shape of all the constituents in the melt-spun alloys also varied from the contact surface towards the free surface of the ribbons. The smallest constituents were established at the contact surface, measuring less than 0.1 μm, to 0.5 μm at the free surface. The grains of the aluminium-rich matrix had mean diameters of less than 20 μm, close to the free surface, down to 1 μm at the contact surface.</p

Room temperature deformation of in-situ grown quasicrystals embedded in Al-based cast alloy

An Al-based cast alloy containing Mn, Be and Cu has been chosen to investigate the room temperature deformation behavior of QC particles embedded in Al-matrix. Using LOM, SEM (equipped with EDS), conventional TEM with SAED and controlled tensile and compression tests, the deformation response of AlMn2Be2Cu2 cast alloy at room temperature has been examined. Alloy consisted of Al-based matrix, primary particles and eutectic icosahedral quasicrystalline (QC i-phase) and traces of Θ-Al2Cu and Al10Mn3. Tensile and compression specimens were used for evaluation of mechanical response and behavior of QC i-phase articles embedded in Al-cast alloy. It has been established that embedded QC i-phase particles undergo plastic deformation along with the Al-based matrix even under severe deformation and have the response resembling that of the metallic materials by formation of typical cup-and-cone feature prior to failure. So, we can conclude that QC i-phase has the ability to undergo plastic deformation along with the Al-matrix to greater extent contrary to e.g. intermetallics such as Θ-Al2Cu for instance

Room temperature deformation of in-situ grown quasicrystals embedded in Al-based cast alloy

An Al-based cast alloy containing Mn, Be and Cu has been chosen to investigate the room temperature deformation behavior of QC particles embedded in Al-matrix. Using LOM, SEM (equipped with EDS), conventional TEM with SAED and controlled tensile and compression tests, the deformation response of AlMn2Be2Cu2 cast alloy at room temperature has been examined. Alloy consisted of Al-based matrix, primary particles and eutectic icosahedral quasicrystalline (QC i-phase) and traces of Θ-Al2Cu and Al10Mn3. Tensile and compression specimens were used for evaluation of mechanical response and behavior of QC i-phase articles embedded in Al-cast alloy. It has been established that embedded QC i-phase particles undergo plastic deformation along with the Al-based matrix even under severe deformation and have the response resembling that of the metallic materials by formation of typical cup-and-cone feature prior to failure. So, we can conclude that QC i-phase has the ability to undergo plastic deformation along with the Al-matrix to greater extent contrary to e.g. intermetallics such as Θ-Al2Cu for instance

INFLUENCE OF COOLING RATE AND ALLOYING ELEMENTS ON THE MICROSTRUCTURE OF THE Al-Mn-BASED ALLOY

Aluminum-based alloys have been used extensively for the past five decades primarily due to their good strength vs. specific weight ratio. Numerous methods and techniques have been devised to further improve mechanical properties of these alloys as they are often used in the transport applications. Influence of the cooling rate and chemical composition on the constitution of Al-Mn-based alloy has been investigated. Elements such as B, Be, C, Ca, Cu, Fe, Mg, Si, Sr and Ti have been introduced to Al-Mn alloys in order to study their influence. Changes in cooling rates during casting using permanent copper molds with different sized troughs have also been monitored. Combined influence of changes in chemical composition and cooling rates was followed using LOM, SEM, EDS, DAS measurement and mathematic modeling. It has been established that Al-Mn-based alloys form a lot of different phases during synthesis and solidification, mostly crystalline intermetallics, but also in some cases quasicrystalline (QC) ones, especially when cooling rates exceed 500 Ks-1. QCs are currently also considered as an alternative for reinforcement of Al-Mn-based alloys. It was found that in the case of alloy system Al-Mn-Cu-Be and cooling rates between 500 and 1350 Ks-1 the preferred phase formed was an icosahedral QC phase or iQC. Icosahedral QC phase formed as the primary phase and in some cases also in the form of the quasicrystalline eutectic (αAl + iQC). Additions of B, C, Ca, Ti and Sr have not proven to be effective in promoting formation of quasicrystals in cast Al-Mn alloys whilst Fe, Cu, Mg and Si proved to be highly efficient.Aluminum-based alloys have been used extensively for the past five decades primarily due to their good strength vs. specific weight ratio. Numerous methods and techniques have been devised to further improve mechanical properties of these alloys as they are often used in the transport applications. Influence of the cooling rate and chemical composition on the constitution of Al-Mn-based alloy has been investigated. Elements such as B, Be, C, Ca, Cu, Fe, Mg, Si, Sr and Ti have been introduced to Al-Mn alloys in order to study their influence. Changes in cooling rates during casting using permanent copper molds with different sized troughs have also been monitored. Combined influence of changes in chemical composition and cooling rates was followed using LOM, SEM, EDS, DAS measurement and mathematic modeling. It has been established that Al-Mn-based alloys form a lot of different phases during synthesis and solidification, mostly crystalline intermetallics, but also in some cases quasicrystalline (QC) ones, especially when cooling rates exceed 500 Ks-1. QCs are currently also considered as an alternative for reinforcement of Al-Mn-based alloys. It was found that in the case of alloy system Al-Mn-Cu-Be and cooling rates between 500 and 1350 Ks-1 the preferred phase formed was an icosahedral QC phase or iQC. Icosahedral QC phase formed as the primary phase and in some cases also in the form of the quasicrystalline eutectic (αAl + iQC). Additions of B, C, Ca, Ti and Sr have not proven to be effective in promoting formation of quasicrystals in cast Al-Mn alloys whilst Fe, Cu, Mg and Si proved to be highly efficient

Način skrućivanja kompleksne metalne Al-Mn-Be legure

The solidification paths of the Al86.1Mn2.5Be11.4 and Al84Mn5.1Be10.9 alloys, melt spun, cast into a copper mould and controlled cooled (during DSC) were investigated by means of light-optical microscopy (LOM), differential scanning calorimetry (DSC) combined with thermogravimetry (TG) or simultaneous thermal analysis (STA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Auger electron spectroscopy (AES) and the X-ray diffraction (XRD) line in Elletra Trieste, Italy. The constitutions of samplesfrom both alloys were examined in all three states, i.e., after melt spinning, after casting into a copper mould and after differential scanning calorimetry. It was established that in the cast and controlled-cooled specimens the alloys consisted of an aluminium-rich ▫$alpha$▫Al-matrix, and the Al4Mn and Be4AlMn phases. In the case of casting and DSC the primary crystallization began with the precipitation of the Be4AlMn phase, followed by what can most likely be characterized as a uni-variant binary eutectic reaction L > (Be4AlMn + Al4Mn). The solidification process continued with an invariant ternary eutectic reaction, where the remaining melt (L) formed the heterogeneous structure (▫$alpha$▫Al + Al4Mn + Be4AlMn) or a ternary eutectic. When extremely high cooling rates were employed, as is the case with melt-spinning,the constituting phases of both alloys were precipitated in a very small form and the Be4AlMn phase was completely absent in the form of primary polygonal particles and replaced by the icosahedral quasicrystalline phase or the i-phase. There was also no evidence of the Al4Mn phase. The distribution, size and shape of all the constituents in the melt-spun alloys also varied from the contact surface towards the free surface of the ribbons. The smallest constituents were established at the contact surface, measuring less than 0.1 ▫$mu$▫m, to 0.5 ▫$mu$▫m at the free surface. The grains of the aluminium-rich matrix had mean diameters of less than 20 ▫$mu$▫m, close to the freesurface, down to 1 m at the contact surface.Načini skrućivanja Al86.1B2.5 Be11.4 i Al84Mn5.1Be10.9 legura dobivenih lijevanjem pri velikim brzinama hlađenja ("melt-spinning" metoda), u bakrenu kokilu i uz kontrolirano hlađenje (za vrijeme DSC) istraživani su metodama optičke mikroskopije (LOM), diferencijalno pretražne kalorimetrije (DSC) u kombinaciji s termogravimetrijom (TG) ili simultanom toplinskom analizom (STA), pretražne elektronske mikroskopije (SEM), transmisijske elektronske mikroskopije (TEM), spektroskopije Augerovih elektrona (AES) i rendgenske difrakcije (XRD). Konstituenti uzoraka iz obje legure su ispitivani za tri različita stanja, tj. nakon izrazito brzog hlađenja, lijevanja u bakrenu kokilu i nakon diferencijalno pretražne kalorimetrije. Utvrđeno je da su se uzorci legura u lijevanom i kontrolirano hlađenom stanju sastojali od aluminijem bogate αAl-osnove, te Al10Mn3 i Be4AlMn faza. U slučaju lijevanja i diferencijalno pretražne kalorimetrije primarna je kristalizacija započela precipitacijom B4AlMn faze što se može najvjerojatnije okarakterizirati kao univarijantna binarna eutektička reakcija L > (Be4AlMn + Al10Mn3). Proces skrućivanja je nastavljen s invarijantnom ternarnom eutektičkom reakcijom, gdje preostala talina (L) stvara heterogenu strukturu (αAl + Al10Mn3 + Be4AlMn) ili ternarni eutektik. Kada su korištene izrazito velike brzine hlađenja, kao u slučaju "melt-spinning" metode, konstitutivne faze obiju legura su precipitirale u veoma malom obliku, a Be4AlMn faza bila je potpuno odsutna u obliku primarnih poligonalnih čestica i zamijenjena je "icosahedral" kristaliničnom fazom ili i-fazom. Također nema dokaza o prisutnosti Al10Mn3 faze. Raspodjela, veličina i oblik svih konstituenata u brzo-hladećim legurama su se promijenili od kontakne površine prema slobodnoj površini trakica, s manje od 0.1 µm pa do 0.5 µm kod slobodne površine. Zrna aluminijem bogate osnove imala su, blizu slobodne površine, srednji promjer manji od 20 µm, a kod kontakne površine srednji promjer zrna se smanjio na 1 µm

Utjecaj brizne hlađenja na mikrostrukturu legure Al94Mn2Be2Cu2

In this study the effect of the cooling rate on the microstructure of Al94 Mn2 Be2 Cu2 alloy was investigated. The vacuum induction melted and cast alloy was exposed to different cooling rates. The slowest cooling rate was achieved by the DSC (10 K·min^−1), the moderate cooling rate succeeded by casting in the copper mould (≈1 000 K·s−1) and the rapid solidification was performed by melt spinning (up to 10^6 K·s^−1). The microstructure of the DSC-sample consisted of α-Al matrix, and several intermetallics: τ1-Al29 Mn6 Cu4 , Al4 Mn, θ-Al2 Cu and Be4 Al(Mn,Cu). The microstructures of the alloy at moderate and rapid cooling consisted of the α-Al matrix, i-phase and θ-Al2 Cu. Particles of i-phase and θ-Al2 Cu were much smaller and more uniformly distributed in melt-spun ribbons.U ovoj je studiji istraživan utjecaj brzine hlađenja na mikrostrukturu legure Al94Mn2Be2Cu2. Legura sintetizirana vakuumskim indukcionim taljenjem i postupkom lijevanja bila je izložena različitim brzinama hlađenja. Najsporije je bilo hlađenje kod DSC (10 K•min-1), umjerene brzine hlađenja prilikom lijevanja u bakreni kalup (≈1 000 K•s-1) a najviše brzine skrućivanja postignute su pomoću metode melt spinning (do 106 K•s-1). Mikrostruktura DSC uzoraka sastoji se od matrice α-Al i nekoliko intermetalnih faza: τ1-Al29Mn6Cu4, Al4Mn, θ-Al2Cu i Be4Al(Mn,Cu). Mikrostruktura legura umjereno i brzo hlađenih sastoji se od matrice α-Al, i-faze i θ-Al2Cu. Čestice i-faze i θ-Al2Cu mnogo su manje i ravnomjerno raspoređene u trakama izrađenima metodom melt spinning

The influence of the chemical composition and type of alloy on corrosion performances of some medium strength Al-Mg-Si series of alloys

The effect of the chemical composition, i.e. content of silicone (Si) and other alloying elements (Zr, Mn, etc) on the corrosion behaviour and mechanical properties of Al-Mg-Si (6xxx) type alloys was investigated in this paper. Open circuit corrosion potential (OCP) measurements, linear polarization and potentiodynamic anodic/cathodic polarization were employed in order to determine the corrosion behaviour of artificially aged Al-Mg-Si samples in the chloride ions containing aqueous corrosion solutions. The difference in OCPs for the tested 6xxx type alloys in relation to the standard AA1020 alloy was observed to be between 1-4%, except for the AlMg0.65Si0.76Zr0.1 alloy when the difference was 14% (about 100 mV). The presence of zirconium and manganese in AlMgSi0.7 base alloy, that contains small excess of Si, shifts the OCPs to more negative values for -15 mV (~2%) and -88 mV (~11%) in natural water and 0,51 mol NaCl, respectively. All the tested 6xxx type alloys, except AlMg0.7Si1.2Mn0.8, show almost the same corrosion rates and other corrosion characteristics in chloride solution, with mass loss per year between 2.3-3 g/m2 . http://dx.doi.org/10.5937/metmateng1402131

The influence of the chemical composition and type of alloy on corrosion performances of some medium strength Al-Mg-Si series of alloys

The effect of the chemical composition, i.e. content of silicone (Si) and other alloying elements (Zr, Mn, etc) on the corrosion behaviour and mechanical properties of Al-Mg-Si (6xxx) type alloys was investigated in this paper. Open circuit corrosion potential (OCP) measurements, linear polarization and potentiodynamic anodic/cathodic polarization were employed in order to determine the corrosion behaviour of artificially aged Al-Mg-Si samples in the chloride ions containing aqueous corrosion solutions. The difference in OCPs for the tested 6xxx type alloys in relation to the standard AA1020 alloy was observed to be between 1-4%, except for the AlMg0.65Si0.76Zr0.1 alloy when the difference was 14% (about 100 mV). The presence of zirconium and manganese in AlMgSi0.7 base alloy, that contains small excess of Si, shifts the OCPs to more negative values for -15 mV (~2%) and -88 mV (~11%) in natural water and 0,51 mol NaCl, respectively. All the tested 6xxx type alloys, except AlMg0.7Si1.2Mn0.8, show almost the same corrosion rates and other corrosion characteristics in chloride solution, with mass loss per year between 2.3-3 g/m2

The influence of age hardening and shot peening on the surface properties of 7075 aluminium alloy

The present study investigates the effect of shot peening (SP) on the mechanical properties and surface roughness of 7075 aluminum alloy during different stages and conditions of heat treatment. The mechanical properties were determined by measuring Vickers microhardness profiles and residual stress profiles, while the amount of alloying elements present in the solid solution of the samples under different heat treatment conditions was determined by measuring the electrical conductivity. The results show that the increase in microhardness near the SP surface and the maximum compressive residual stresses are mainly related to the content of alloying elements in the solid solution. Surface roughness increases with increasing SP Almen intensity, and samples with the highest microhardness and residual stresses have the lowest surface roughness