TY - JOUR

T1 - Synthesis of bulk reactive Ni-Al composites using high pressure torsion

AU - Renk, Oliver

AU - Tkadletz, Michael

AU - Kostoglou, Nikolaos

AU - Gunduz, Ibrahim Emre

AU - Fezzaa, K.

AU - Sun, T.

AU - Stark, Andreas

AU - Doumanidis, Charalabos C.

AU - Eckert, Jürgen

AU - Pippan, Reinhard

AU - Mitterer, Christian

AU - Rebholz, Claus

N1 - Publisher Copyright: © 2020 Elsevier B.V.

PY - 2021/3/15

Y1 - 2021/3/15

N2 - Self-propagating exothermic reactions, for instance in the nickel-aluminum (Ni–Al) system, have been widely studied to create high performance intermetallic compounds or for in-situ welding. Their easy ignition once the phase spacing is reduced below the micron scale, makes top-down methods like high-energy ball milling, ideal to fabricate such reactive nanostructures. A major drawback of ball milling is the need of a sintering step to form bulk pieces of the reactive material. However, this is not possible, as the targeted reactions would already proceed. Therefore, we investigate the ability of high pressure torsion as an alternative process, capable to produce bulk nanocomposites from powder mixtures. Severe straining of powder mixtures with a composition of 50 wt% Ni and 50 wt% Al enables fabrication of self-reactive bulk samples with microstructures similar to those obtained from ball milling or magnetron sputtering. Samples deformed at ambient temperature are highly reactive and can be ignited significantly below the Al melting point, finally predominantly consisting of Al 3Ni 2 and Al 3Ni, independent of the applied strain. Although the reaction proceeds first at the edge of the disk, the strain gradient present in the disks does not prevent reaction of the whole sample.

AB - Self-propagating exothermic reactions, for instance in the nickel-aluminum (Ni–Al) system, have been widely studied to create high performance intermetallic compounds or for in-situ welding. Their easy ignition once the phase spacing is reduced below the micron scale, makes top-down methods like high-energy ball milling, ideal to fabricate such reactive nanostructures. A major drawback of ball milling is the need of a sintering step to form bulk pieces of the reactive material. However, this is not possible, as the targeted reactions would already proceed. Therefore, we investigate the ability of high pressure torsion as an alternative process, capable to produce bulk nanocomposites from powder mixtures. Severe straining of powder mixtures with a composition of 50 wt% Ni and 50 wt% Al enables fabrication of self-reactive bulk samples with microstructures similar to those obtained from ball milling or magnetron sputtering. Samples deformed at ambient temperature are highly reactive and can be ignited significantly below the Al melting point, finally predominantly consisting of Al 3Ni 2 and Al 3Ni, independent of the applied strain. Although the reaction proceeds first at the edge of the disk, the strain gradient present in the disks does not prevent reaction of the whole sample.

UR - http://www.scopus.com/inward/record.url?scp=85093982010&partnerID=8YFLogxK

U2 - 10.1016/j.jallcom.2020.157503

DO - 10.1016/j.jallcom.2020.157503

M3 - Article

VL - 857.2021

JO - Journal of alloys and compounds

JF - Journal of alloys and compounds

SN - 0925-8388

IS - 15 March

M1 - 157503

ER -