Deformation Behavior of α 2-Lamellae in Fully Lamellar Ti-48Al-2Mn-2Nb at Room Temperature

Abstract

The alloy Ti-48at.% Al-2at.% Mn-2at.% Nb (Ti-48Al-2Mn-2Nb) is a member of a new class of generic two-phase TiAl based alloys which will be referred to as {gamma}-alloys in the following. In general, polycrystalline {gamma}-alloys will always contain a number of lamellar grains which exhibit hard orientation behavior during loading. As a result, it may be predicted that the plastic properties of the minority {alpha}{sub 2}-Ti{sub 3}Al phase critically affect the deformation and fracture behavior of {gamma}-alloys containing lamellar colonies. Hence, in order to understand the plasticity and strength of {gamma}-alloys it is important to elucidate the deformation behavior of the {alpha}{sub 2}-Ti{sub 3}Al lamellae during loading in the hard orientations. In the present work the deformation modes in hard oriented grains of room temperature compressed fully lamellar Ti-48Al-2Mn-2Nb have been studied by transmission electron microscopy (TEM). Particular attention has been paid to the deformation characteristics exhibited by the {alpha}{sub 2}-lamellae and to deformation transfer processes between the two constituent phases. In this paper the results obtained for lamellar grains loaded approximately parallel to the interface normal, [0001]{alpha}{sub 2}//[111]{gamma}, are presented and discussed with respect to mechanical properties of {gamma}-alloys.