Can local hot spots induce α₂/γ lamellae during incomplete massive transformation of γ-TiAl alloys?

TY - JOUR

T1 - Can local hot spots induce α2/γ lamellae during incomplete massive transformation of γ-TiAl alloys?

AU - Fischer, F. D.

AU - Cha, L.

AU - Dehm, G.

AU - Clemens, H.

N1 - Funding Information: The authors appreciate the funding by Austrian FWF under the project “Massive Transformation – Experiments and Simulations”, Project number P20709-N20 . Financial support by the Austrian Federal Government (in particular from the Bundesministerium für Verkehr, Innovation und Technologie and the Bundesministerium für Wirtschaft und Arbeit) and the Styrian Provincial Government , represented by Österreichische Forschungsförderungsgesellschaft mbH and by Steirische Wirtschaftsförderungsgesellschaft mbH, within the research activities of the K2 Competence Center on “Integrated Research in Materials, Processing and Product Engineering”, operated by the Materials Center Leoben Forschung GmbH in the framework of the Austrian COMET Competence Center Programme, is gratefully acknowledged.

PY - 2010/5

Y1 - 2010/5

N2 - Oil quenching is applied to a Ti-45Al-7.5b alloy (in at%) in order to investigate the occurrence of local "hot spots" during rapid cooling from the single α-phase region. After quenching the microstructure consists of large α2-Ti3Al grains and a small volume fraction of massively transformed γm-TiAl particles. The majority of the γm-particles show a featureless α2/γm interface, whereas in the immediate vicinity of some γm-particles lamellar α2/γ-structures exist, exhibiting a Blackburn orientation relationship. The extension into the α2-parent grain is in the range of 1-10 μm. In this study it is investigated, if the diffusion-controlled formation of the γ-laths is triggered by the release of latent heat during the α → γm transformation, which leads to a local increase in temperature by a hot spot effect. A theoretical model is presented, which describes the temperature conditions around the hot spot. The model predicts that the life time of the hot spot is much too short to generate γ-laths observed with a length of 1-10 μm.

AB - Oil quenching is applied to a Ti-45Al-7.5b alloy (in at%) in order to investigate the occurrence of local "hot spots" during rapid cooling from the single α-phase region. After quenching the microstructure consists of large α2-Ti3Al grains and a small volume fraction of massively transformed γm-TiAl particles. The majority of the γm-particles show a featureless α2/γm interface, whereas in the immediate vicinity of some γm-particles lamellar α2/γ-structures exist, exhibiting a Blackburn orientation relationship. The extension into the α2-parent grain is in the range of 1-10 μm. In this study it is investigated, if the diffusion-controlled formation of the γ-laths is triggered by the release of latent heat during the α → γm transformation, which leads to a local increase in temperature by a hot spot effect. A theoretical model is presented, which describes the temperature conditions around the hot spot. The model predicts that the life time of the hot spot is much too short to generate γ-laths observed with a length of 1-10 μm.

KW - A. Titanium aluminides

KW - B. Heat treatment

KW - D. Microstructure

UR - http://www.scopus.com/inward/record.url?scp=77950299802&partnerID=8YFLogxK

U2 - 10.1016/j.intermet.2010.01.017

DO - 10.1016/j.intermet.2010.01.017

M3 - 文章

AN - SCOPUS:77950299802

SN - 0966-9795

VL - 18

SP - 972

EP - 976

JO - Intermetallics

JF - Intermetallics

IS - 5

ER -