On the role of twinning during room temperature deformation of γ-TiAl based alloys

Overview of constitutive laws, kinematics, homogenization and multiscale methods in crystal plasticity finite-element modeling: Theory, experiments, applications

“…in glassy matter) [208,209], mechanical twinning [164][165][166]169] and even superplastic grain boundary shear [41,45]. The CPFE method allows the user to implement these shear mechanisms including their interactions.…”

“…Such transformations create shears with kinematics similar to that of dislocations. Two such mechanisms and their incorporation into the CPFE framework will be discussed here, namely martensite formation [74,80] and mechanical twinning [164][165][166]169]. Martensite formation takes place via a shear-induced change of the crystal structure which, as a rule, involves a volume change.…”

Microstructural study of pre-yielding and pre-yield cracking in TiAl-based alloys

“…Similarly further work [5,6] on duplex Ti46.5Al-4(Nb, Cr, Ta, B) was again interpreted totally in terms of twinning because no cracks were observed. The fact that the twins formed during the later stages of deformation did not give rise to acoustic emission was explained on the basis that these twins tended to be much shorter than those formed at yield because twin blocking, caused by twins on non-parallel {111}, occurs [4][5][6].…”

“…Similarly further work [5,6] on duplex Ti46.5Al-4(Nb, Cr, Ta, B) was again interpreted totally in terms of twinning because no cracks were observed. The fact that the twins formed during the later stages of deformation did not give rise to acoustic emission was explained on the basis that these twins tended to be much shorter than those formed at yield because twin blocking, caused by twins on non-parallel {111}, occurs [4][5][6]. There is Intermetallics 14 (2006) clearly disagreement about the role of twinning and of cracking on the generation of acoustic signals between the work in these papers [4][5][6] and the observations presented earlier and in the preceding paper, [1][2][3].…”

Modelling of texture evolution in metals accounting for lattice reorientation due to twinning

“…Twinning mechanism is also a significant mechanism of plastic deformation at room temperature in the case of hcp materials such like magnesium, zirconium or Ti alloys (Agnew et al, 2001;Karaman et al, 2000;Kaschner et al, 2006;Salem et al, 2005;Staroselsky and Anand, 2003) and intermetallics (Fischer et al, 2003;Marketz et al, 2002;Mecking et al, 1996). For these materials, twinning enables to compensate for the lack of five independent slip systems required for a general shape change of volume elements.…”