Results for “Mg(AlC)2” | Engineering Papers

DOE OSTI2020

Materials Data on Mg(AlC)2 by Materials Project

Al2MgC2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Mg2+ is bonded to six equivalent C4- atoms to form MgC6 octahedra that share corners with twelve equivalent AlC4 tetrahedra, edges with six equivalent MgC6 octahedra, and edges with six equivalent AlC4 tetrahedra. All Mg–C bond lengths are 2.51 Å. Al3+ is bonded to four equivalent C4- atoms to form AlC4 tetrahedra that share corners with six equivalent MgC6 octahedra, corners with six equivalent AlC4 tetrahedra, edges with three equivalent MgC6 octahedra, and edges with three equivalent AlC4 tetrahedra. The corner-sharing octahedra tilt angles range from 25–51°. There are three shorter (2.01 Å) and one longer (2.21 Å) Al–C bond lengths. C4- is bonded in a 7-coordinate geometry to three equivalent Mg2+ and four equivalent Al3+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Thermodynamic Modeling of the Al-Ce-Cu-Mg-Si System and Its Application to Aluminum-Cerium Alloy Design

Recently discovered AlCe alloys have shown promise in a number of applications, but the propensity of Ce to react with Al and other alloying elements can complicate the phase equilibria and design approach. To solve this, the CALPHAD method is used to explore an alloy within the quinary Al-Ce-Cu-Mg-Si system by developing a thermodynamic database with self-consistent parameters. The database includes a description of all 10 binary systems and 8 ternary systems consisting of: (i) 6 Al-containing ternaries (Al-Ce-Cu, Al-Ce-Mg, Al-Ce-Si, Al-Cu-Mg, Al-Cu-Si and Al-Mg-Si); and (ii) 2 additional ternaries that include Mg and Si (i.e., Ce-Mg-Si and Cu-Mg-Si). The thermodynamic description for the Al-Ce-Mg and Al-Mg-Si systems were reassessed to ensure consistency with the binary systems and the Ce-Mg-Si system is presented for the first time and compared to theoretical data from DFT (Density Functional Theory). In addition to the ternary interactions, the quaternary compound Al3Cu2Mg9Si7 and solid solution extending from the ternary Al2CuMg phase (Al,Si)2CuMg are incorporated. The CALPHAD method is employed and leveraged through the use of a Materials Design Simulator (MDS) to accelerate the design of novel aluminum-cerium-based alloys. The combination of a CALPHAD-based framework with experimental efforts and industrial insight permits the development of three new Al-Ce alloys: Al-3.5Ce-0.4Mg-7Si (Ce-modified A356), Al-5Ce-1Cu-0.5Mg-10Si and Al-19Ce-0.9Mg-1.1Si.

36 MATERIALS SCIENCE↗