摘要
用高压透射电镜研究了Ti-54wt%Ni形状记忆合金B2相的选区电子衍射花样中的漫散射条纹。动态加热观察表明漫散射条纹与B2相的晶格的不稳定性有关。倾斜样品观察表明漫散射条纹来自穿过基本倒易阵点的倒易壁。对不同晶带轴的衍射花样中的漫散射条纹的分析表明,花样中的漫散射条纹通常有三个方向,条纹互相交叉形成网络,每根条纹都由几段组成。提出漫散射条纹是由穿过基本倒易阵点且位于{112}倒易平面上的尺度有限的倒易壁形成的。用波矢位于{112}倒易平面上的横向声学声子波对电子的散射,讨论了倒易壁的形成和分布以及花样中的漫散射条纹的长度。
The Ti-54wt% Ni shape memory alloy has been invest igated with a HVEM. It was found that the intense diffuse scattered streaks appeared in SADPs of B2-phase. In situ observation during heating showed that the streaks were related to the instability of the crystal lattice of B2-phase. SADPS taken form an area during tilting a specimen show that the diffuse scattered streaks are formed from the rel walls intersecting fundamental reciprocal points. SADPs of B2- Phase with the zone axises [012], [023], [011], [(?)33], [(?)33], [(?)11] and [(?)35] were taken. These SADPs show that the diffuse scattered streaks in SADPs usually lie in three different directions, intersect each other and form a network. Each streak consists of several sections. These sections lie in a line only in the [111] SADP. The sections are parallel each other, but do not lie in a line in other SADPs. Diffuse scattered streaks do not intersect the super-structure diffraction spots and centre spot, but the fundamental diffraction spots and can intersect each other at the positions without the diffraction spot. It can be assumed that the diffuse scattered streaks are formed by the rel walls lying on the {112}~* planes, intersecting at the fundamental points of the reciprocal lattice, and with certain dimensions. The rel walls can be used to explain the geometric characteristics of the diffuse scattered streaks and the change of angles between streaks in different SADPs. Finally, the formation and distribution of the rel walls as well as the length of diffuse scattered streaks in SADPs have also been discussed according to the diffuse scattering of electron by the transverse acoustic phonon waves with the wave vector lying on {112}~* planes in the lattice of B2-phase.
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
1993年第6期13-20,共8页
Rare Metal Materials and Engineering
关键词
漫散射条纹
电子衍射花样
钛镍合金
diffuse scattered streak SADP of single crystal B2-phase shape memory alloy
