TY - JOUR
T1 - Evolution of lattice defects, disordered/ordered phase transformations and mechanical properties in Ni-Al-Ti intermetallics by high-pressure torsion
AU - Edalati, Kaveh
AU - Daio, Takeshi
AU - Horita, Zenji
AU - Kishida, Kyosuke
AU - Inui, Haruyuki
N1 - Funding Information:
One of the authors (K.E.) thanks the Japan Society for Promotion of Science (JSPS) for a postdoctoral scholarship. This work was supported in part by the Light Metals Educational Foundation of Japan, in part by a Grant-in-Aid for Scientific Research from the MEXT, Japan, in Innovative Areas “Bulk Nanostructured Metals”, in part by Kyushu University Interdisciplinary Programs in Education and Projects in Research Development (P&P), in part by Grant-in-Aid for Scientific Research (A) (no. 24246113) from the MEXT, Japan, and in part by the Advanced Low Carbon Technology Research and Development Program of the Japan Science and Technology Agency (JST).
PY - 2013/6/25
Y1 - 2013/6/25
N2 - Powder mixtures of Ni-25 mol.% Al-25 mol.% Ti were subjected to severe plastic deformation using high-pressure torsion (HPT) to examine the formation of ternary ordered intermetallics. In consistency with the Al-Ni and Ti-Al systems, in which the in situ formation of binary ordered intermetallics was achieved during HPT, a partially-ordered nanostructured B2-Ni(Al,Ti) phase with ∼11 nm grain size and high dislocation density, >1016 m 2, was formed in the Ni-Al-Ti system. The hardness-strain behavior of the Ni-Al-Ti mixture was similar to pure aluminum having a hardness maximum followed by a strain softening at large strains. The B2 phase transformed to a fully-ordered Ni2AlTi phase with L21 structure after annealing at 873 K with an activation energy of 270 kJ/mol. Atomic-scale elemental mapping using scanning transmission electron microscopy confirmed the occurrence of ordering after annealing as well as partial twining. Micropillar compression tests showed that both yield stress and plasticity increased after annealing, and high strength and high ductility with values as 3.6 GPa and 7%, respectively, were achieved.
AB - Powder mixtures of Ni-25 mol.% Al-25 mol.% Ti were subjected to severe plastic deformation using high-pressure torsion (HPT) to examine the formation of ternary ordered intermetallics. In consistency with the Al-Ni and Ti-Al systems, in which the in situ formation of binary ordered intermetallics was achieved during HPT, a partially-ordered nanostructured B2-Ni(Al,Ti) phase with ∼11 nm grain size and high dislocation density, >1016 m 2, was formed in the Ni-Al-Ti system. The hardness-strain behavior of the Ni-Al-Ti mixture was similar to pure aluminum having a hardness maximum followed by a strain softening at large strains. The B2 phase transformed to a fully-ordered Ni2AlTi phase with L21 structure after annealing at 873 K with an activation energy of 270 kJ/mol. Atomic-scale elemental mapping using scanning transmission electron microscopy confirmed the occurrence of ordering after annealing as well as partial twining. Micropillar compression tests showed that both yield stress and plasticity increased after annealing, and high strength and high ductility with values as 3.6 GPa and 7%, respectively, were achieved.
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U2 - 10.1016/j.jallcom.2013.02.128
DO - 10.1016/j.jallcom.2013.02.128
M3 - Article
AN - SCOPUS:84875029231
VL - 563
SP - 221
EP - 228
JO - Journal of Alloys and Compounds
JF - Journal of Alloys and Compounds
SN - 0925-8388
ER -