Solidification paths and eutectic intermetallic phases in Mg–Al–Ca ternary alloys

Suzuki, Akihito; Saddock, Nicholas D.; Jones, J. W.; Pollock, Tresa M.

doi:10.1016/j.actamat.2005.03.001

Cited by 307 publications

(178 citation statements)

References 17 publications

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“…The stability of the intermetallic C36 phase during annealing at 300 °C was examined in die-cast Mg-5Al-3Ca based alloys. The C36 phase transformed to the C15 (Al 2 Ca) phase by a shear-assisted mechanism [20] . Precipitates of the C15 Laves phase were also found within the α-Mg grains in die-cast Mg-5Al-3Ca-0.15Sr alloy as a result of aging in the temperature range from 175 °C to 350 °C [21] .…”

Section: Microstructure Observation Before Andmentioning

confidence: 99%

Creep resistance of as-cast Mg-5Al-5Ca-2Sn alloy

et al. 2017

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I ncreasing attention has been paid due to increased demand of heat resistant magnesium alloys by heatresistant parts, such as powertrain and transmission components [1] for lightweight vehicles. Mg-Al system is one focus for development of this kind of materials. In alloying elements, calcium makes a most attractive option since it provides acceptable levels of castability and increased corrosion and creep resistance at low cost in comparison with RE [2][3][4] . The addition of Ca to the MgAl system resulted in high pressure die casting MRI230D and MRI153 alloys, both of which present significantly better creep resistance than AE42 alloy [5,6] . Mg-Sn-based alloys have great potential for creep resistance because of the formation of thermally stable Mg 2 Sn phase in the as-cast condition, and many Ca-containing Mg-Sn alloys exhibit good creep resistance [4,[7][8][9][10][11] . Therefore, the consideration for the development of Mg-Al-Sn-Ca alloy becomes necessary. In our previous studies, Mg-5Al-5Ca-2Sn (AXT552) presents good thermal stability [12] due to the formation of connected hard skeleton [13] composed of Abstract: In the present study, creep properties of as-cast Mg-5Al-5Ca-2Sn (AXT552) alloy were investigated by means of a GWT304 creep testing machine at temperatures of 175 °C and 200 °C in the stress range of 35-90 MPa. Results show that creep rates increase with applied stress at an identical temperature. Creep strain at 100 hours is 0.0518% and 0.083% at creep conditions of 175°C/75MPa and 200°C/60MPa, respectively, which is comparable to MRI230D and much lower than most of AX series alloys. By the observation and analysis for samples before and after creep tests using a Shimadzu XRD-7000 type X-ray diffractometer (XRD) and a Hitachi S-3400N type scanning electron microscope (SEM), it was found that Al 2 Ca (C15) phase precipitated out of C36 phase or matrix. The cavity formation and connection at the interface of soft matrix and hard intermetallics caused the propagation of cracking along the eutectic phase during creep process and dislocation accommodated grain/ phase boundary sliding is expected to be the dominant creep mechanism.Key words: as-cast AXT552 alloy; creep properties; creep rate; creep strain; microstructure Al 2 Ca and (Mg,Al) 2 Ca compounds. It was found that the skeleton is able to effectively shield load from the softer α-Mg matrix [14] and increase the creep resistance of the alloys [15,16] . Therefore, the tensile creep property of ascast AXT552 alloy at temperatures of 175 °C and 200 °C was checked and compared with other heat-resistant Mg alloys in this study. Experimental procedureMg-5Al-5Ca-2Sn (wt.%), or AXT552, alloy was prepared using commercial Mg, Al, Sn (with purity of 99.9%) metals and Mg-20Ca master alloy. The alloy was melted in a mild steel crucible under the protection of a mixed gas atmosphere of 1% SF 6 and 99% Ar. After the master alloy added was melted, the melt was held at 750 °C for 10 min, and then poured into a cylindrical mold made of cast iron with a diam...

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Section: Microstructure Observation Before Andmentioning

confidence: 99%

Creep resistance of as-cast Mg-5Al-5Ca-2Sn alloy

et al. 2017

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“…The charge transfer from Ca atoms to Mg atoms demonstrates the ionic bonding in CaMg 2 crystal. It is found that the charge transfer from Ca to Mg decreases with the increasing pressure, implying that the ionic bonding is getting weaker [8] under the higher pressure.…”

Section: Analysis Of Mulliken Electron Population and Debye Temperaturementioning

confidence: 97%

“…It is evident that the total DOS of CaMg 2 decreases with elevated pressure, which implies that applied pressure is of benefit to the stability of CaMg 2 . Moreover, CaMg 2 is characterised to have the metallic behaviour as there is no energy gap near the Fermi level [2,6,8,9]. The main bonding peak is located in the energy region from -2 to 4eV, originated from the contribution of valence electron numbers of Mg s, Mg p, Ca s and Ca p orbits.…”

Section: Prediction Of Elastic Moduli Of Camg2 Ploycrystalsmentioning

confidence: 99%

“…Mg-Ca alloy exhibits excellent oxidation-resistance and burning-resistance [5], and it is also regarded as one of the most promising alloy due to its appreciable corrosion resistance [6]. CaMg 2 Laves phase as its excellent physical and chemical properties is a typical phase in Mg-Y-Ni [7] and Mg-Al-Ca alloy [8]. Yu et al [9] investigated the electronic structure and elastic properties of the binary AB2 type Laves phase in Mg-Al-Ca alloys.…”

Section: Introductionmentioning

confidence: 99%

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Electronic and Elastic Properties of CaMg₂Alloy Phase under Various Pressures by Density Functional Theory

Lin

Chen

et al. 2016

MATEC Web Conf.

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Abstract. The influencing effect of pressure on structural, elastic and electronic properties of CaMg2 Laves phase is mainly investigated. The optimized structural parameters at zero pressure are a=b=6.250Å, c=10.101Å, which has good agreement with the experimental and theoretical values. The elastic constants are calculated, and then the bulk modulus, shear modulus, Young's modulus, Poisson's ratio and anisotropy factor are determined. The results show that the applied pressure is beneficial to the elastic properties of CaMg2. The analysis of electronic density of states (DOS) and Mulliken electron population reveal the bonding characteristics in CaMg2 crystal. Finally, the Debye temperatures under different pressures are obtained from the average sound velocity.

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“…Studies advocated it for the first time that the experimental and theoretical research is primarily focused on the thermodynamic properties and phase stability Mg2X (X=Ni) alloy aspect [3][4][5][6][7]. Although, previous studies demonstrated that the speed hydrogen storage is slow at room temperature, and hydrogen desolation temperature is so high that hydrogen is difficult to store in the aspects of kinetic releasing performance.…”

Section: Introductionmentioning

confidence: 99%

Thermal Stability of the Mg2Ni-Based Hydrogen Storage Alloy Doped Ti Element

Li¹,

Zhang²,

Kong³

et al. 2016

IJHT

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Crystal structures, electronic structures, thermal stability and dehydrogenation energy of Mg-based hydrogen storage materials were investigated via the first-principle calculations, and the calculations of bonding properties, electronic structure, band structure, density of state, charge density difference and electronic structure of Mg2Ni alloy were examined. Namely, the work mainly took account of doping metal elements Ti to replace Mg and Ni elements in different proportions portion, and then form different crystals, including Mg12Ni6, Mg1.5NiTiMg(2)1/2, Mg5/3NiTiMg(2)1/3, Mg2NiH4, Mg2Ni3/4Ti1/4H4 aimed to improve the hydrogen storage characteristics of Mg-based metal hydrides. The results manifested Ti elements may hold the center position of octahedral sites, and the investigation further indicated that the hydrogen release performance and the thermal stability of hydrogen became lower through calculating absorption reaction enthalpy. Additionally, the metals Ti with high electronegativity interstitially exhibit useful effects on the characteristics of Mg-based hydrogen storage, which is beneficial to find the impact of the mechanism in terms of the electronic structure, and provide the theoretical support for designing new hydrogen storage materials.

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Solidification paths and eutectic intermetallic phases in Mg–Al–Ca ternary alloys

Cited by 307 publications

References 17 publications

Creep resistance of as-cast Mg-5Al-5Ca-2Sn alloy

Creep resistance of as-cast Mg-5Al-5Ca-2Sn alloy

Electronic and Elastic Properties of CaMg₂Alloy Phase under Various Pressures by Density Functional Theory

Thermal Stability of the Mg2Ni-Based Hydrogen Storage Alloy Doped Ti Element

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Solidification paths and eutectic intermetallic phases in Mg–Al–Ca ternary alloys

Cited by 307 publications

References 17 publications

Creep resistance of as-cast Mg-5Al-5Ca-2Sn alloy

Creep resistance of as-cast Mg-5Al-5Ca-2Sn alloy

Electronic and Elastic Properties of CaMg2Alloy Phase under Various Pressures by Density Functional Theory

Thermal Stability of the Mg2Ni-Based Hydrogen Storage Alloy Doped Ti Element

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Electronic and Elastic Properties of CaMg₂Alloy Phase under Various Pressures by Density Functional Theory