Numéro
J. Phys. IV France
Volume 03, Numéro C7, Novembre 1993
The 3rd European Conference on Advanced Materials and Processes
Troisiéme Conférence Européenne sur les Matériaux et les Procédés Avancés
Page(s) C7-377 - C7-382
DOI http://dx.doi.org/10.1051/jp4:1993759
The 3rd European Conference on Advanced Materials and Processes
Troisiéme Conférence Européenne sur les Matériaux et les Procédés Avancés

J. Phys. IV France 03 (1993) C7-377-C7-382

DOI: 10.1051/jp4:1993759

Solidification and metastable phase formation in conventional and planar flow cast Ti-48.8at%Al-2.2at%V

G. SHAO, T. GROSDIDIER and P. TSAKIROPOULOS

Department of Material Science and Engineering, University of Surrey, Guildford GU2 5XH, U.K.


Abstract
The solidification paths and subsequent solid state transformations of conventional and planar flow cast Ti-48.8at.%Al-2.2at.%V alloy were studied. At low cooling rates, [MATH] is the first phase to form from the melt. The primary hexagonal dendrites subsequently underwent the [MATH] solid state transformation resulting in a lath structure made of {111} [MATH] twins separated by thin [MATH] layers. The Al rich interdendritic areas consisted of [MATH] solidified from the segregated melt. Under higher cooling rates, [MATH] is the first phase to form from the melt. This was confirmed by the lath-free microstructure of the dendrites and by the fact that these dendrites were richer in Al than the interdendritic area leading to reverse segregation. The Al lean areas were [MATH] formed from an [MATH] parent phase by either the massive [MATH] or the [MATH] solid state transformations. For the largest melt undercoolings, the microstructure was free of chemical segregation and disordered [MATH] formed directly from the melt. Extremely fine networks of ordered domains were also observed, showing the subsequent ordering process of the [MATH] phase.



© EDP Sciences 1993