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10 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

From phase decomposition to evaporation: A multi-modal evaluation of thermally degraded model lightweight high-entropy alloy

Lightweight high-entropy alloys (LHEAs) have the potential to replace conventional lightweight materials due to their superior mechanical properties and thermal stability. However, the thermal degradation pattern of LHEAs from phase decomposition to evaporation is not clear. We develop a new Al-based dual phase (FCC + HCP) LHEA—AlTi 0.45 CuZn, and further investigate its thermal degradation behavior for potential high-temperature structural applications. Using multimodal advanced characterization techniques such as differential scanning calorimetry/thermogravimetric analysis, scanning/transmission electron microscopy, and synchrotron X-ray diffraction/pair distribution function (XRD/PDF), a sequence of thermal degradation events beyond the thermal phase stability limit—between 250 and 360 °C—is observed. These include phase decomposition at ~360 °C, Zn evaporation at ~750 °C, and LHEA melting at 880 °C which results in ~25% cumulative weight loss. The formation of Al-Ti phase off the AlTi 0.45 CuZn matrix is due to the largest negative mixing enthalpy for Al-Ti than other binary pairs. Similarly, Zn evaporation from AlTi 0.45 CuZn LHEA is due to its faster evaporation rate than other constituent elements. The high-resolution synchrotron XRD and PDF results support the aforementioned observations; in addition, they reveal local atomic arrangements, local strain, and sluggish grain growth in the LHEA. Among other LHEAs of close density range (5.55 ≤ ρ ≤ 5.85 g/cc), the investigated LHEA exhibits outstanding nano-indentation hardness values due to the coupled grain size effect and HCP phase strengthening of the FCC matrix. As the search for LHEAs for lightweight applications grows, this study shows the potential use of AlTi 0.45 CuZn LHEA for structural applications even at elevated temperatures.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

Materials Data on TiAl2 by Materials Project

TiAl2 is beta Cu3Ti-like structured and crystallizes in the orthorhombic Cmmm space group. The structure is three-dimensional. Ti is bonded to two equivalent Ti and ten Al atoms to form distorted TiTi2Al10 cuboctahedra that share corners with four equivalent AlTi4Al8 cuboctahedra, corners with eight equivalent TiTi2Al10 cuboctahedra, edges with four equivalent TiTi2Al10 cuboctahedra, edges with twenty AlTi4Al8 cuboctahedra, faces with seven equivalent TiTi2Al10 cuboctahedra, and faces with eleven AlTi4Al8 cuboctahedra. Both Ti–Ti bond lengths are 3.01 Å. There are a spread of Ti–Al bond distances ranging from 2.73–2.89 Å. There are three inequivalent Al sites. In the first Al site, Al is bonded to four equivalent Ti and eight Al atoms to form AlTi4Al8 cuboctahedra that share corners with four equivalent AlTi4Al8 cuboctahedra, corners with eight equivalent TiTi2Al10 cuboctahedra, edges with eight equivalent TiTi2Al10 cuboctahedra, edges with sixteen equivalent AlTi6Al6 cuboctahedra, faces with six equivalent TiTi2Al10 cuboctahedra, and faces with twelve AlTi4Al8 cuboctahedra. There are four shorter (2.81 Å) and four longer (2.90 Å) Al–Al bond lengths. In the second Al site, Al is bonded to four equivalent Ti and eight Al atoms to form AlTi4Al8 cuboctahedra that share corners with twelve AlTi4Al8 cuboctahedra, edges with eight equivalent AlTi6Al6 cuboctahedra, edges with sixteen equivalent TiTi2Al10 cuboctahedra, faces with four equivalent TiTi2Al10 cuboctahedra, and faces with fourteen AlTi4Al8 cuboctahedra. All Al–Al bond lengths are 2.88 Å. In the third Al site, Al is bonded to six equivalent Ti and six Al atoms to form AlTi6Al6 cuboctahedra that share corners with twelve AlTi4Al8 cuboctahedra, edges with eight equivalent TiTi2Al10 cuboctahedra, edges with sixteen AlTi4Al8 cuboctahedra, faces with six equivalent TiTi2Al10 cuboctahedra, and faces with twelve AlTi4Al8 cuboctahedra. Both Al–Al bond lengths are 2.72 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ti3Al by Materials Project

Ti3Al is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Ti is bonded to eight equivalent Ti and four equivalent Al atoms to form TiTi8Al4 cuboctahedra that share corners with four equivalent AlTi12 cuboctahedra, corners with fourteen equivalent TiTi8Al4 cuboctahedra, edges with six equivalent AlTi12 cuboctahedra, edges with twelve equivalent TiTi8Al4 cuboctahedra, faces with four equivalent AlTi12 cuboctahedra, and faces with sixteen equivalent TiTi8Al4 cuboctahedra. There are a spread of Ti–Ti bond distances ranging from 2.82–2.93 Å. There are two shorter (2.84 Å) and two longer (2.88 Å) Ti–Al bond lengths. Al is bonded to twelve equivalent Ti atoms to form AlTi12 cuboctahedra that share corners with six equivalent AlTi12 cuboctahedra, corners with twelve equivalent TiTi8Al4 cuboctahedra, edges with eighteen equivalent TiTi8Al4 cuboctahedra, faces with eight equivalent AlTi12 cuboctahedra, and faces with twelve equivalent TiTi8Al4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TiAl by Materials Project

TiAl is Tetraauricupride structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Ti is bonded to four equivalent Ti and eight equivalent Al atoms to form TiTi4Al8 cuboctahedra that share corners with twelve equivalent TiTi4Al8 cuboctahedra, edges with eight equivalent TiTi4Al8 cuboctahedra, edges with sixteen equivalent AlTi8Al4 cuboctahedra, faces with eight equivalent AlTi8Al4 cuboctahedra, and faces with ten equivalent TiTi4Al8 cuboctahedra. All Ti–Ti bond lengths are 2.82 Å. All Ti–Al bond lengths are 2.85 Å. Al is bonded to eight equivalent Ti and four equivalent Al atoms to form AlTi8Al4 cuboctahedra that share corners with twelve equivalent AlTi8Al4 cuboctahedra, edges with eight equivalent AlTi8Al4 cuboctahedra, edges with sixteen equivalent TiTi4Al8 cuboctahedra, faces with eight equivalent TiTi4Al8 cuboctahedra, and faces with ten equivalent AlTi8Al4 cuboctahedra. All Al–Al bond lengths are 2.82 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TiAl3 by Materials Project

Al3Ti is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ti is bonded to twelve Al atoms to form TiAl12 cuboctahedra that share corners with four equivalent TiAl12 cuboctahedra, corners with eight equivalent AlTi4Al8 cuboctahedra, edges with eight equivalent TiAl12 cuboctahedra, edges with sixteen equivalent AlTi4Al8 cuboctahedra, faces with four equivalent TiAl12 cuboctahedra, and faces with fourteen AlTi4Al8 cuboctahedra. There are four shorter (2.72 Å) and eight longer (2.88 Å) Ti–Al bond lengths. There are two inequivalent Al sites. In the first Al site, Al is bonded to four equivalent Ti and eight equivalent Al atoms to form AlTi4Al8 cuboctahedra that share corners with four equivalent AlTi4Al8 cuboctahedra, corners with eight equivalent TiAl12 cuboctahedra, edges with twenty-four AlTi4Al8 cuboctahedra, faces with six equivalent TiAl12 cuboctahedra, and faces with twelve AlTi4Al8 cuboctahedra. All Al–Al bond lengths are 2.88 Å. In the second Al site, Al is bonded to four equivalent Ti and eight Al atoms to form AlTi4Al8 cuboctahedra that share corners with twelve equivalent AlTi4Al8 cuboctahedra, edges with eight equivalent TiAl12 cuboctahedra, edges with sixteen AlTi4Al8 cuboctahedra, faces with four equivalent TiAl12 cuboctahedra, and faces with fourteen AlTi4Al8 cuboctahedra. All Al–Al bond lengths are 2.72 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TiAl2 by Materials Project

TiAl2 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4_1/amd space group. The structure is three-dimensional. Ti is bonded to two equivalent Ti and ten Al atoms to form distorted TiTi2Al10 cuboctahedra that share corners with four equivalent AlTi4Al8 cuboctahedra, corners with eight equivalent TiTi2Al10 cuboctahedra, edges with four equivalent TiTi2Al10 cuboctahedra, edges with twenty AlTi6Al6 cuboctahedra, faces with seven equivalent TiTi2Al10 cuboctahedra, and faces with eleven AlTi4Al8 cuboctahedra. Both Ti–Ti bond lengths are 3.03 Å. There are a spread of Ti–Al bond distances ranging from 2.74–2.87 Å. There are two inequivalent Al sites. In the first Al site, Al is bonded to six equivalent Ti and six Al atoms to form AlTi6Al6 cuboctahedra that share corners with twelve AlTi6Al6 cuboctahedra, edges with eight equivalent TiTi2Al10 cuboctahedra, edges with sixteen AlTi4Al8 cuboctahedra, faces with six equivalent TiTi2Al10 cuboctahedra, and faces with twelve AlTi6Al6 cuboctahedra. There are a spread of Al–Al bond distances ranging from 2.72–2.90 Å. In the second Al site, Al is bonded to four equivalent Ti and eight Al atoms to form AlTi4Al8 cuboctahedra that share corners with four equivalent TiTi2Al10 cuboctahedra, corners with eight AlTi6Al6 cuboctahedra, edges with twelve equivalent TiTi2Al10 cuboctahedra, edges with twelve equivalent AlTi6Al6 cuboctahedra, faces with five equivalent TiTi2Al10 cuboctahedra, and faces with thirteen AlTi6Al6 cuboctahedra. All Al–Al bond lengths are 2.81 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TiAl3 by Materials Project

Al3Ti is Uranium Silicide structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Ti is bonded to twelve equivalent Al atoms to form TiAl12 cuboctahedra that share corners with twelve equivalent TiAl12 cuboctahedra, edges with twenty-four equivalent AlTi4Al8 cuboctahedra, faces with six equivalent TiAl12 cuboctahedra, and faces with twelve equivalent AlTi4Al8 cuboctahedra. All Ti–Al bond lengths are 2.81 Å. Al is bonded to four equivalent Ti and eight equivalent Al atoms to form AlTi4Al8 cuboctahedra that share corners with twelve equivalent AlTi4Al8 cuboctahedra, edges with eight equivalent TiAl12 cuboctahedra, edges with sixteen equivalent AlTi4Al8 cuboctahedra, faces with four equivalent TiAl12 cuboctahedra, and faces with fourteen equivalent AlTi4Al8 cuboctahedra. All Al–Al bond lengths are 2.81 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ti3Al by Materials Project

Ti3Al is alpha bismuth trifluoride structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. there are two inequivalent Ti sites. In the first Ti site, Ti is bonded in a distorted body-centered cubic geometry to four equivalent Ti and four equivalent Al atoms. All Ti–Ti bond lengths are 2.80 Å. All Ti–Al bond lengths are 2.80 Å. In the second Ti site, Ti is bonded in a distorted body-centered cubic geometry to eight equivalent Ti and six equivalent Al atoms. All Ti–Al bond lengths are 3.23 Å. Al is bonded in a distorted body-centered cubic geometry to fourteen Ti atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ti2Al by Materials Project

Ti2Al is half-Heusler-derived structured and crystallizes in the cubic F-43m space group. The structure is three-dimensional. there are two inequivalent Ti sites. In the first Ti site, Ti is bonded in a body-centered cubic geometry to four equivalent Ti and four equivalent Al atoms. All Ti–Ti bond lengths are 2.73 Å. All Ti–Al bond lengths are 2.73 Å. In the second Ti site, Ti is bonded in a 10-coordinate geometry to four equivalent Ti and six equivalent Al atoms. All Ti–Al bond lengths are 3.15 Å. Al is bonded in a 4-coordinate geometry to ten Ti atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TiAl3 by Materials Project

Al3Ti is Magnesium-derived structured and crystallizes in the orthorhombic Pmm2 space group. The structure is three-dimensional. Ti is bonded to two equivalent Ti and ten Al atoms to form TiTi2Al10 cuboctahedra that share corners with eight equivalent AlTi4Al8 cuboctahedra, corners with ten equivalent TiTi2Al10 cuboctahedra, edges with two equivalent TiTi2Al10 cuboctahedra, edges with sixteen AlTi4Al8 cuboctahedra, faces with four equivalent TiTi2Al10 cuboctahedra, and faces with sixteen AlTi4Al8 cuboctahedra. Both Ti–Ti bond lengths are 2.84 Å. There are a spread of Ti–Al bond distances ranging from 2.83–2.85 Å. There are three inequivalent Al sites. In the first Al site, Al is bonded to four equivalent Ti and eight Al atoms to form AlTi4Al8 cuboctahedra that share corners with eight equivalent TiTi2Al10 cuboctahedra, corners with ten equivalent AlTi4Al8 cuboctahedra, edges with four equivalent TiTi2Al10 cuboctahedra, edges with fourteen AlTi4Al8 cuboctahedra, faces with four equivalent TiTi2Al10 cuboctahedra, and faces with sixteen AlTi4Al8 cuboctahedra. There are two shorter (2.84 Å) and six longer (2.86 Å) Al–Al bond lengths. In the second Al site, Al is bonded to four equivalent Ti and eight Al atoms to form AlTi4Al8 cuboctahedra that share corners with eighteen AlTi4Al8 cuboctahedra, edges with eight equivalent TiTi2Al10 cuboctahedra, edges with ten AlTi4Al8 cuboctahedra, faces with four equivalent TiTi2Al10 cuboctahedra, and faces with sixteen AlTi4Al8 cuboctahedra. There are a spread of Al–Al bond distances ranging from 2.81–2.85 Å. In the third Al site, Al is bonded to two equivalent Ti and ten Al atoms to form AlTi2Al10 cuboctahedra that share corners with eighteen AlTi4Al8 cuboctahedra, edges with four equivalent TiTi2Al10 cuboctahedra, edges with fourteen AlTi4Al8 cuboctahedra, faces with eight equivalent TiTi2Al10 cuboctahedra, and faces with twelve AlTi4Al8 cuboctahedra. Both Al–Al bond lengths are 2.84 Å.

36 MATERIALS SCIENCE↗