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10 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

The physical metallurgy of mechanically-alloyed, dispersion-strengthened Al-Li-Mg and Al-Li-Cu alloys

Powder processing of Al-Li-Mg and Al-Li-Cu alloys by mechanical alloying (MA) is described, with a discussion of physical and mechanical properties of early experimental alloys of these compositions. The experimental samples were mechanically alloyed in a Szegvari attritor, extruded at 343 and 427 C, and some were solution-treated at 520 and 566 C and naturally, as well as artificially, aged at 170, 190, and 210 C for times of up to 1000 hours. All alloys exhibited maximum hardness after being aged at 170 C; lower hardness corresponds to the solution treatment at 566 C than to that at 520 C. A comparison with ingot metallurgy alloys of the same composition shows the MA material to be stronger and more ductile. It is also noted that properly aged MA alloys can develop a better combination of yield strength and notched toughness at lower alloying levels.

Gilman, P. S.↗
NASA NTRS1991

Characterization of the dimensional stability of advanced metallic materials using an optical test bench structure

The dimensional stability of low-density high specific-strength metal-matrix composites (including 30 vol pct SiC(p)/SXA 24-T6 Al, 25 vol pct SiC(p)/6061-T6 Al, 40 vol pct graphite P100 fiber/6061 Al, 50 vol pct graphite P100 fiber/6061 Al, and 40 vol pct P100 graphite fiber/AZ91D Mg composites) and an Al-Li-Mg metal alloy was evaluated using a specially designed five-strut optical test bench structure. The structure had 30 thermocouple locations, one retroreflector, one linear interferometer multilayer insulation, and various strip heaters. It was placed in a 10 exp -7 torr capability vacuum chamber with a laser head positioned at a window port, and a laser interferometer system for collecting dimensional change data. It was found that composite materials have greater 40-C temporal dimensional stability than the AL-Li-Mg alloy. Aluminum-based composites demonstrated better 40-C temporal stability than Mg-based composites.

Hsieh, Cheng↗
NASA NTRS1983

Stress-corrosion behavior of aluminum-lithium alloys in aqueous environments

The stress corrosion susceptibility of two powder metallurgy (P/M) alloys, Al-Li-Cu and Al-Li-Cu-Mg two mechanically attrited (M/A) alloys, Al-Li-Cu and Al-Li-Mg; and two wrought, ingot alloys, X-2020 and AA7475, are compared. Time-dependent fracture in an aqueous sodium chloride environment under alternate immersion condition was found to vary significantly between alloys. The stress corrosion behavior of the two powder metallurgy processed alloys was studied in detail under conditions of crack initiation, static crack growth, and fatigue crack growth. A variety of stress corrosion tests were performed including smooth surface, time-to-failure tests; potentiostatic tests on smooth surfaces exposed to constant applied strain rates; and fracture mechanics-type tests under static and cyclic loads. Both alloys show surface pitting and subsequent intergranular corrosion. Pitting is more severe in the magnesium-bearing alloy and is associated with stringer particles strung along the extrusion direction as a result of P/M processing.

Pizzo, P. P.↗
NASA NTRS1984

Stress-corrosion behavior of aluminum-lithium alloys in aqueous salt environments

The stress corrosion susceptibility of two powder metallurgy (P/M) alloys, Al-Li-Cu and Al-Li-Cu-Mg; two mechanically attrited (M/A) alloys, Al-Li-Cu and Al-Li-Mg; and two wrought, ingot alloys, X-2020 and AA7475, are compared. Time-dependent fracture in an aqueous sodium chloride environment under alternate immersion condition was found to vary significantly between alloys. The stress corrosion behavior of the two powder metallurgy processed alloys was studied in detail under conditions of crack initiation, static crack growth, and fatigue crack growth. A variety of stress corrosion tests were performed including smooth surface, time-to-failure tests; potentiostatic tests on smooth surfaces exposed to constant applied strain rates; and fracture mechanics-type tests under static and cyclic loads. Both alloys show surface pitting and subsequent intergranular corrosion. Pitting is more severe in the magnesium-bearing alloy and is associated with stringer particles strung along the extrusion direction as a result of P/M processing.

Pizzo, P. P.↗
NASA NTRS1987

Advanced powder metallurgy aluminum alloys via rapid solidification technology, phase 2

Marko's rapid solidification technology was applied to processing high strength aluminum alloys. Four classes of alloys, namely, Al-Li based (class 1), 2124 type (class 2), high temperature Al-Fe-Mo (class 3), and PM X7091 type (class 4) alloy, were produced as melt-spun ribbons. The ribbons were pulverized, cold compacted, hot-degassed, and consolidated through single or double stage extrusion. The mechanical properties of all four classes of alloys were measured at room and elevated temperatures and their microstructures were investigated optically and through electron microscopy. The microstructure of class 1 Al-Li-Mg alloy was predominantly unrecrystallized due to Zr addition. Yield strengths to the order of 50 Ksi were obtained, but tensile elongation in most cases remained below 2 percent. The class 2 alloys were modified composition of 2124 aluminum alloy, through addition of 0.6 weight percent Zr and 1 weight percent Ni. Nickel addition gave rise to a fine dispersion of intermetallic particles resisting coarsening during elevated temperature exposure. The class 2 alloy showed good combination of tensile strength and ductility and retained high strength after 1000 hour exposure at 177 C. The class 3 Al-Fe-Mo alloy showed high strength and good ductility both at room and high temperatures. The yield and tensile strength of class 4 alloy exceeded those of the commercial 7075 aluminum alloy.

Ray, Ranjan↗
DOE OSTI2020

Materials Data on Li(Mg4Al3)4 by Materials Project

Li(Mg4Al3)4 is gamma-brass-derived structured and crystallizes in the monoclinic Cm space group. The structure is three-dimensional. Li is bonded in a 12-coordinate geometry to seven Mg and five Al atoms. There are a spread of Li–Mg bond distances ranging from 2.98–3.14 Å. There are a spread of Li–Al bond distances ranging from 2.87–3.22 Å. There are ten inequivalent Mg sites. In the first Mg site, Mg is bonded in a 12-coordinate geometry to seven Mg and five Al atoms. There are a spread of Mg–Mg bond distances ranging from 3.05–3.14 Å. There are a spread of Mg–Al bond distances ranging from 2.91–3.18 Å. In the second Mg site, Mg is bonded in a 1-coordinate geometry to one Li, three Mg, and six Al atoms. There are two shorter (3.05 Å) and one longer (3.18 Å) Mg–Mg bond lengths. There are a spread of Mg–Al bond distances ranging from 3.07–3.17 Å. In the third Mg site, Mg is bonded in a 12-coordinate geometry to four Mg and twelve Al atoms. There are two shorter (3.13 Å) and one longer (3.15 Å) Mg–Mg bond lengths. There are a spread of Mg–Al bond distances ranging from 3.18–3.22 Å. In the fourth Mg site, Mg is bonded in a 10-coordinate geometry to four Mg and six Al atoms. Both Mg–Mg bond lengths are 3.03 Å. There are four shorter (3.08 Å) and two longer (3.09 Å) Mg–Al bond lengths. In the fifth Mg site, Mg is bonded in a 12-coordinate geometry to one Li, six Mg, and five Al atoms. There are a spread of Mg–Mg bond distances ranging from 3.05–3.19 Å. There are a spread of Mg–Al bond distances ranging from 2.88–3.15 Å. In the sixth Mg site, Mg is bonded in a 12-coordinate geometry to one Li, six Mg, and five Al atoms. There are a spread of Mg–Mg bond distances ranging from 3.12–3.18 Å. There are a spread of Mg–Al bond distances ranging from 2.90–3.19 Å. In the seventh Mg site, Mg is bonded in a 12-coordinate geometry to seven Mg and five Al atoms. There are a spread of Mg–Mg bond distances ranging from 3.13–3.17 Å. There are a spread of Mg–Al bond distances ranging from 2.90–3.19 Å. In the eighth Mg site, Mg is bonded in a 10-coordinate geometry to four Mg and six Al atoms. There are one shorter (3.04 Å) and one longer (3.05 Å) Mg–Mg bond lengths. There are a spread of Mg–Al bond distances ranging from 3.07–3.12 Å. In the ninth Mg site, Mg is bonded in a 12-coordinate geometry to one Li, six Mg, and five Al atoms. The Mg–Mg bond length is 3.15 Å. There are a spread of Mg–Al bond distances ranging from 2.89–3.17 Å. In the tenth Mg site, Mg is bonded in a 12-coordinate geometry to seven Mg and five Al atoms. There are a spread of Mg–Al bond distances ranging from 2.90–3.16 Å. There are seven inequivalent Al sites. In the first Al site, Al is bonded in a distorted q6 geometry to eight Mg and three Al atoms. There are one shorter (2.70 Å) and two longer (2.77 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 11-coordinate geometry to one Li, seven Mg, and three Al atoms. There are a spread of Al–Al bond distances ranging from 2.69–2.76 Å. In the third Al site, Al is bonded in a 11-coordinate geometry to one Li, seven Mg, and three Al atoms. There are one shorter (2.70 Å) and one longer (2.73 Å) Al–Al bond lengths. In the fourth Al site, Al is bonded in a 11-coordinate geometry to eight Mg and three Al atoms. There are a spread of Al–Al bond distances ranging from 2.69–2.76 Å. In the fifth Al site, Al is bonded in a 11-coordinate geometry to eight Mg and three Al atoms. The Al–Al bond length is 2.75 Å. In the sixth Al site, Al is bonded in a 11-coordinate geometry to one Li, seven Mg, and three Al atoms. In the seventh Al site, Al is bonded in a 11-coordinate geometry to eight Mg and three Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Li(Mg4Al3)4 by Materials Project

Li(Mg4Al3)4 crystallizes in the cubic I-43m space group. The structure is three-dimensional. Li is bonded in a 4-coordinate geometry to four equivalent Mg and twelve equivalent Al atoms. All Li–Mg bond lengths are 3.08 Å. All Li–Al bond lengths are 3.21 Å. There are two inequivalent Mg sites. In the first Mg site, Mg is bonded in a 12-coordinate geometry to seven Mg and five equivalent Al atoms. There are a spread of Mg–Mg bond distances ranging from 3.06–3.16 Å. There are a spread of Mg–Al bond distances ranging from 2.90–3.16 Å. In the second Mg site, Mg is bonded in a 10-coordinate geometry to one Li, three equivalent Mg, and six equivalent Al atoms. All Mg–Al bond lengths are 3.07 Å. Al is bonded in a 11-coordinate geometry to one Li, seven Mg, and three equivalent Al atoms. There are one shorter (2.70 Å) and two longer (2.77 Å) Al–Al bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiMg2Al by Materials Project

LiMg2Al crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Li is bonded to two equivalent Li, two equivalent Mg, and four equivalent Al atoms to form distorted LiLi2Mg2Al4 hexagonal bipyramids that share corners with two equivalent AlLi4Mg2Al2 hexagonal bipyramids, corners with six equivalent LiLi2Mg2Al4 hexagonal bipyramids, edges with four equivalent LiLi2Mg2Al4 hexagonal bipyramids, edges with eight equivalent AlLi4Mg2Al2 hexagonal bipyramids, and edges with twelve MgLiMg6Al hexagonal bipyramids. Both Li–Li bond lengths are 2.90 Å. Both Li–Mg bond lengths are 2.98 Å. All Li–Al bond lengths are 2.98 Å. There are two inequivalent Mg sites. In the first Mg site, Mg is bonded to one Li, six Mg, and one Al atom to form distorted MgLiMg6Al hexagonal bipyramids that share corners with eight MgLiMg6Al hexagonal bipyramids, edges with six equivalent LiLi2Mg2Al4 hexagonal bipyramids, edges with six AlLi4Mg2Al2 hexagonal bipyramids, and edges with twelve MgLiMg6Al hexagonal bipyramids. The Mg–Li bond length is 2.98 Å. There are two shorter (2.90 Å) and four longer (2.98 Å) Mg–Mg bond lengths. The Mg–Al bond length is 2.93 Å. In the second Mg site, Mg is bonded to one Li, six Mg, and one Al atom to form distorted MgLiMg6Al hexagonal bipyramids that share corners with eight equivalent MgLiMg6Al hexagonal bipyramids, edges with six equivalent LiLi2Mg2Al4 hexagonal bipyramids, edges with six AlLi4Mg2Al2 hexagonal bipyramids, and edges with twelve MgLiMg6Al hexagonal bipyramids. Both Mg–Mg bond lengths are 2.90 Å. The Mg–Al bond length is 2.93 Å. There are two inequivalent Al sites. In the first Al site, Al is bonded to four equivalent Li, two equivalent Mg, and two equivalent Al atoms to form distorted AlLi4Mg2Al2 hexagonal bipyramids that share corners with two equivalent LiLi2Mg2Al4 hexagonal bipyramids, corners with six equivalent AlLi4Mg2Al2 hexagonal bipyramids, edges with four equivalent AlLi4Mg2Al2 hexagonal bipyramids, edges with eight equivalent LiLi2Mg2Al4 hexagonal bipyramids, and edges with twelve MgLiMg6Al hexagonal bipyramids. All Al–Li bond lengths are 2.98 Å. Both Al–Al bond lengths are 2.90 Å. In the second Al site, Al is bonded to four equivalent Li, two Mg, and two equivalent Al atoms to form distorted AlLi4Mg2Al2 hexagonal bipyramids that share corners with two equivalent LiLi2Mg2Al4 hexagonal bipyramids, corners with six equivalent AlLi4Mg2Al2 hexagonal bipyramids, edges with four equivalent AlLi4Mg2Al2 hexagonal bipyramids, edges with eight equivalent LiLi2Mg2Al4 hexagonal bipyramids, and edges with twelve MgLiMg6Al hexagonal bipyramids. The Al–Mg bond length is 2.93 Å. Both Al–Al bond lengths are 2.90 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiMg17Al11 by Materials Project

LiMg17Al11 is gamma-brass-derived structured and crystallizes in the monoclinic Cm space group. The structure is three-dimensional. Li is bonded in a 11-coordinate geometry to eight Mg and three Al atoms. There are a spread of Li–Mg bond distances ranging from 2.93–3.21 Å. There are one shorter (2.71 Å) and two longer (2.76 Å) Li–Al bond lengths. There are eleven inequivalent Mg sites. In the first Mg site, Mg is bonded in a 10-coordinate geometry to four Mg and six Al atoms. There are three shorter (3.04 Å) and one longer (3.16 Å) Mg–Mg bond lengths. There are a spread of Mg–Al bond distances ranging from 3.06–3.13 Å. In the second Mg site, Mg is bonded in a 12-coordinate geometry to one Li, seven Mg, and four Al atoms. There are four shorter (3.14 Å) and two longer (3.15 Å) Mg–Mg bond lengths. There are two shorter (3.00 Å) and two longer (3.19 Å) Mg–Al bond lengths. In the third Mg site, Mg is bonded in a 12-coordinate geometry to one Li, four Mg, and eleven Al atoms. There are two shorter (3.11 Å) and one longer (3.20 Å) Mg–Mg bond lengths. There are a spread of Mg–Al bond distances ranging from 3.16–3.24 Å. In the fourth Mg site, Mg is bonded in a 10-coordinate geometry to four Mg and six Al atoms. There are two shorter (3.04 Å) and one longer (3.07 Å) Mg–Mg bond lengths. There are a spread of Mg–Al bond distances ranging from 3.08–3.11 Å. In the fifth Mg site, Mg is bonded in a 12-coordinate geometry to seven Mg and five Al atoms. There are two shorter (3.12 Å) and four longer (3.13 Å) Mg–Mg bond lengths. There are a spread of Mg–Al bond distances ranging from 2.91–3.21 Å. In the sixth Mg site, Mg is bonded in a 12-coordinate geometry to one Li, seven Mg, and four Al atoms. There are a spread of Mg–Mg bond distances ranging from 3.05–3.21 Å. There are a spread of Mg–Al bond distances ranging from 2.91–3.18 Å. In the seventh Mg site, Mg is bonded in a 12-coordinate geometry to one Li, seven Mg, and four Al atoms. There are a spread of Mg–Mg bond distances ranging from 3.12–3.15 Å. There are a spread of Mg–Al bond distances ranging from 2.91–3.23 Å. In the eighth Mg site, Mg is bonded in a 12-coordinate geometry to seven Mg and five Al atoms. There are a spread of Mg–Mg bond distances ranging from 3.13–3.21 Å. There are a spread of Mg–Al bond distances ranging from 2.91–3.18 Å. In the ninth Mg site, Mg is bonded in a 10-coordinate geometry to one Li, four Mg, and five Al atoms. There are one shorter (3.05 Å) and one longer (3.06 Å) Mg–Mg bond lengths. There are a spread of Mg–Al bond distances ranging from 3.06–3.13 Å. In the tenth Mg site, Mg is bonded in a 12-coordinate geometry to seven Mg and five Al atoms. The Mg–Mg bond length is 3.15 Å. There are a spread of Mg–Al bond distances ranging from 2.91–3.17 Å. In the eleventh Mg site, Mg is bonded in a 12-coordinate geometry to seven Mg and five Al atoms. There are a spread of Mg–Al bond distances ranging from 2.90–3.19 Å. There are six inequivalent Al sites. In the first Al site, Al is bonded in a 11-coordinate geometry to one Li, eight Mg, and two equivalent Al atoms. Both Al–Al bond lengths are 2.76 Å. In the second Al site, Al is bonded in a 11-coordinate geometry to eight Mg and three Al atoms. There are a spread of Al–Al bond distances ranging from 2.68–2.75 Å. In the third Al site, Al is bonded in a 11-coordinate geometry to one Li, eight Mg, and two Al atoms. There are one shorter (2.71 Å) and one longer (2.73 Å) Al–Al bond lengths. In the fourth Al site, Al is bonded in a 11-coordinate geometry to eight Mg and three Al atoms. There are one shorter (2.70 Å) and one longer (2.73 Å) Al–Al bond lengths. In the fifth Al site, Al is bonded in a distorted q6 geometry to eight Mg and three Al atoms. The Al–Al bond length is 2.78 Å. In the sixth Al site, Al is bonded in a 11-coordinate geometry to eight Mg and three Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Li(Mg4Al3)4 by Materials Project

Li(Mg4Al3)4 crystallizes in the trigonal R3m space group. The structure is three-dimensional. Li is bonded in a 10-coordinate geometry to four Mg and six equivalent Al atoms. There are one shorter (2.99 Å) and three longer (3.04 Å) Li–Mg bond lengths. All Li–Al bond lengths are 3.04 Å. There are five inequivalent Mg sites. In the first Mg site, Mg is bonded in a 12-coordinate geometry to one Li, six Mg, and five Al atoms. There are a spread of Mg–Mg bond distances ranging from 3.15–3.19 Å. There are a spread of Mg–Al bond distances ranging from 2.93–3.14 Å. In the second Mg site, Mg is bonded in a 10-coordinate geometry to four Mg and six Al atoms. There are a spread of Mg–Mg bond distances ranging from 3.03–3.14 Å. There are a spread of Mg–Al bond distances ranging from 3.07–3.11 Å. In the third Mg site, Mg is bonded in a 1-coordinate geometry to one Li, three equivalent Mg, and twelve Al atoms. There are a spread of Mg–Al bond distances ranging from 3.17–3.23 Å. In the fourth Mg site, Mg is bonded in a 12-coordinate geometry to seven Mg and five Al atoms. There are two shorter (3.13 Å) and two longer (3.16 Å) Mg–Mg bond lengths. There are a spread of Mg–Al bond distances ranging from 2.92–3.16 Å. In the fifth Mg site, Mg is bonded in a 12-coordinate geometry to seven Mg and five Al atoms. Both Mg–Mg bond lengths are 3.15 Å. There are a spread of Mg–Al bond distances ranging from 2.92–3.17 Å. There are three inequivalent Al sites. In the first Al site, Al is bonded in a 11-coordinate geometry to eight Mg and three Al atoms. There are one shorter (2.69 Å) and two longer (2.76 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 11-coordinate geometry to eight Mg and three Al atoms. Both Al–Al bond lengths are 2.75 Å. In the third Al site, Al is bonded in a distorted q6 geometry to one Li, seven Mg, and three Al atoms. There are one shorter (2.70 Å) and one longer (2.74 Å) Al–Al bond lengths.

36 MATERIALS SCIENCE↗