The massive transformation in Ti-Al alloys: Mechanistic observations

Research output: Contribution to journalArticlepeer-review

Standard

The massive transformation in Ti-Al alloys : Mechanistic observations. / Zhang, X. D.; Godfrey, S.; Weaver, M.; Strangwood, M.; Threadgill, P.; Kaufman, M. J.; Loretto, M. H.

In: Acta Materialia, Vol. 44, No. 9, 01.01.1996, p. 3723-3734.

Research output: Contribution to journalArticlepeer-review

Harvard

APA

Vancouver

Author

Bibtex

@article{9a48b627a6dd4159819883ebe618638c,
title = "The massive transformation in Ti-Al alloys: Mechanistic observations",
abstract = "The massive α→γm transformation, as observed using analytical transmission electron microscopy, in Ti-49Al, Ti-48Al-2Nb-2Mn, Ti-55Al-25Ta and Ti-50Al-20Ta alloys is described. Conventional solution heating and quenching experiments have been combined with the more rapid quenching possible using electron beam melting in order to provide further insight into the early stages of the transformation in these alloys. It is shown that the γ develops first at grain boundaries as lamellae in one of the grains and that these lamellae intersect and spread into the adjacent grain in a massive manner. Consequently, there is no orientation relationship between the massive gamma (γm) and the grain being consumed whereas there is the expected relation between the γm and the first grain which is inherited from the lamellae. It is further shown that the γm grows as an f.c.c. phase after initially growing with the L10 structure. Furthermore, it is shown that the massive f.c.c. phase then orders to the Ll0 structure producing APDB-like defects which are actually thin 90° domains separating adjacent domains that have the same orientation yet are out of phase. The advancing γm interface tends to facet parallel either to one of its four {111} planes or to the basal plane in the grain being consumed by impinging on existing γ lamellae. Thin microtwins and α2 platelets then form in the γm presumably due, respectively, to transformation stresses and supersaturation of the γm with titanium for alloys containing ∼48% Al; indeed, there is a local depletion in aluminium across the α2 platelets as determined using fine probe microanalysis.",
author = "Zhang, {X. D.} and S. Godfrey and M. Weaver and M. Strangwood and P. Threadgill and Kaufman, {M. J.} and Loretto, {M. H.}",
year = "1996",
month = jan,
day = "1",
doi = "10.1016/1359-6454(95)00453-X",
language = "English",
volume = "44",
pages = "3723--3734",
journal = "Acta Materialia",
issn = "1359-6454",
publisher = "Elsevier",
number = "9",

}

RIS

TY - JOUR

T1 - The massive transformation in Ti-Al alloys

T2 - Mechanistic observations

AU - Zhang, X. D.

AU - Godfrey, S.

AU - Weaver, M.

AU - Strangwood, M.

AU - Threadgill, P.

AU - Kaufman, M. J.

AU - Loretto, M. H.

PY - 1996/1/1

Y1 - 1996/1/1

N2 - The massive α→γm transformation, as observed using analytical transmission electron microscopy, in Ti-49Al, Ti-48Al-2Nb-2Mn, Ti-55Al-25Ta and Ti-50Al-20Ta alloys is described. Conventional solution heating and quenching experiments have been combined with the more rapid quenching possible using electron beam melting in order to provide further insight into the early stages of the transformation in these alloys. It is shown that the γ develops first at grain boundaries as lamellae in one of the grains and that these lamellae intersect and spread into the adjacent grain in a massive manner. Consequently, there is no orientation relationship between the massive gamma (γm) and the grain being consumed whereas there is the expected relation between the γm and the first grain which is inherited from the lamellae. It is further shown that the γm grows as an f.c.c. phase after initially growing with the L10 structure. Furthermore, it is shown that the massive f.c.c. phase then orders to the Ll0 structure producing APDB-like defects which are actually thin 90° domains separating adjacent domains that have the same orientation yet are out of phase. The advancing γm interface tends to facet parallel either to one of its four {111} planes or to the basal plane in the grain being consumed by impinging on existing γ lamellae. Thin microtwins and α2 platelets then form in the γm presumably due, respectively, to transformation stresses and supersaturation of the γm with titanium for alloys containing ∼48% Al; indeed, there is a local depletion in aluminium across the α2 platelets as determined using fine probe microanalysis.

AB - The massive α→γm transformation, as observed using analytical transmission electron microscopy, in Ti-49Al, Ti-48Al-2Nb-2Mn, Ti-55Al-25Ta and Ti-50Al-20Ta alloys is described. Conventional solution heating and quenching experiments have been combined with the more rapid quenching possible using electron beam melting in order to provide further insight into the early stages of the transformation in these alloys. It is shown that the γ develops first at grain boundaries as lamellae in one of the grains and that these lamellae intersect and spread into the adjacent grain in a massive manner. Consequently, there is no orientation relationship between the massive gamma (γm) and the grain being consumed whereas there is the expected relation between the γm and the first grain which is inherited from the lamellae. It is further shown that the γm grows as an f.c.c. phase after initially growing with the L10 structure. Furthermore, it is shown that the massive f.c.c. phase then orders to the Ll0 structure producing APDB-like defects which are actually thin 90° domains separating adjacent domains that have the same orientation yet are out of phase. The advancing γm interface tends to facet parallel either to one of its four {111} planes or to the basal plane in the grain being consumed by impinging on existing γ lamellae. Thin microtwins and α2 platelets then form in the γm presumably due, respectively, to transformation stresses and supersaturation of the γm with titanium for alloys containing ∼48% Al; indeed, there is a local depletion in aluminium across the α2 platelets as determined using fine probe microanalysis.

UR - http://www.scopus.com/inward/record.url?scp=0030241852&partnerID=8YFLogxK

U2 - 10.1016/1359-6454(95)00453-X

DO - 10.1016/1359-6454(95)00453-X

M3 - Article

AN - SCOPUS:0030241852

VL - 44

SP - 3723

EP - 3734

JO - Acta Materialia

JF - Acta Materialia

SN - 1359-6454

IS - 9

ER -