Thermally Activated Deformation of Gum Metal: A Strong Evidence for the Peierls Mechanism of Deformation

Abstract

Compression deformation and stress relaxation tests have been made over a wide temperature range for Ti-based bcc alloy single crystal of Gum Metal composition to elucidate the deformation mechanism. The shear yield stress decreases rapidly with increasing temperature with decreasing slope above room temperature, tending to level off. Activation analysis showed that the activation volume becomes smaller than 10 b 3 (b: the Burgers vector) at high stress, indicating that the deformation is controlled by the Peierls mechanism at low temperature. Similar results have been obtained also for severely cold-swaged polycrystalline Gum Metal with the similar composition. These results contradict the generally accepted dislocation-free mechanism of Gum Metal.

Complex multi-step martensitic twinning process during plastic deformation of the superelastic Ti-20Zr-3Mo-3Sn alloy

“…7d, which highlights the occurrence of {130}<310>α" twinning as reported for the specimen strained to 5%. The operation of a reflection on the (130)α" plane or a rotation of 180° around the [3][4][5][6][7][8][9][10]α" direction of the α"-primary crystal leads to the orientation of the observed α"-primary band, confirming the twinning relationship. The (130)α" twinning plane and [3][4][5][6][7][8][9][10]α" twinning direction in martensitic α" phase also coincide with (3-32)β plane and [-113]β direction in Fig.…”

“…Plastic deformation mechanisms are mainly dominated by dislocation glide [10][11][12][13][14][15] or deformation twinning [16][17][18][19][20][21][22][23][24] depending on parent β phase stability, while SIM transformation occurs as a first reversible deformation mechanism in superelastic alloys [1][2][3][4][5][6][7][8][9]13,19,[22][23]. Dislocation glide was investigated through in situ straining TEM experiments in relatively more stable β titanium alloys [11][12][13].…”

Reversion of a Parent {130}⟨310⟩α′′ Martensitic Twinning

“…Deformation of these alloys can be accommodated by several deformation mechanisms such as stress-induced martensitic transformation [1][2][3][4][5][6], dislocation slip [7][8][9][10] and twinning [11][12][13][14][15][16][17][18][19]. While twinning in bcc metals and alloys operates normally with the {112}<111> β system, a unique {332}<113> β twinning system is surprisingly found to be predominant in metastable β titanium alloys.…”

Basic Deformation Mechanism of Bcc Titanium-Based Alloy of Gum Metal

“…In the present paper, detailed results and discussions are presented, though preliminary results have already been reported in Ref. 22). …”