摘要
利用透射电镜在室温变形的γ-TiAl基合金中研究了一种新的形变孪晶与α2片的交截机制。选区电子衍射和矩阵分析结果表明:γ基体中的形变孪晶切过α2片时,如果形变孪晶的宽度与α2片宽度相当,则α2片可以通过K1=狖3031狚,η1=118〈1016〉的孪生机制来协调形变孪晶产生的切变。由于α2片与γ基体之间存在(0001)α2∥狖111狚γ,〈1120〉α2∥〈011〉γ的晶体位向关系,α2片的118〈1016〉狖3031狚切变矢量等价于形变孪晶的切变矢量16〈112犦狖111狚,因此形变孪晶产生的切变可完整地切过α2片而不需要交截区附近γ基体中其它滑移系或孪晶系开动来辅助协调变形。
A new type of intersection mechanism of deformation twins with α2 plates in γ-TiAl based alloy deformed at room temperature was investigated by TEM. Selected area diffraction analysis and matrix operation results show: when a deformation twin in the γ matrix cuts through an α2 plate, it can be deformed by the K 1 = {3 over-bar 31}, η1 = 1/18 [Left Angle Bracket] 101 over-bar 6 [Right Angle Bracket] twining mechanism in order to accommodate the deformation twinning shear if the α2 plate width is comparable to the deformation twin width. The 1/18 [Left Angle Bracket] 101 over-bar 6 [Right Angle Bracket] {3 over-bar 031} shear vector in the α2 plate is equivalent to the 1/6 [Left Angle Bracket] 112]{111 over-bar } shear vector of the deformation twin because of the (0001)α2//{111} γ, [Left Angle Bracket] 112 over-bar 0 [Right Angle Bracket] α2// [Left Angle Bracket] 01 over-bar 1 [Right Angle Bracket] γ crystallographic orientation relationship between the α2 plate and the γ matrix. As a result, the twinning shear can completely cut through the α2 plate without the necessity of activation of other assistant twinning or slip systems in the γ matrix near the intersection to accommodate the residual twinning shear.
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2003年第2期95-98,共4页
Rare Metal Materials and Engineering
