Martensitic Transformation and Phonon Dispersion Relationship

本文测量了Cu-Al-Ni合金母相（_1）和马氏体相（'_1，'_1和'_1）中横向晶格声波（TA模）的声子色散关系与单轴应力的关系<beta><gamma><beta><alpha>。马氏体'_1中的声子色散关系<gamma>在275 MPa以下与单轴应力无关。此外，马氏体“_1”和“_1”中的声子色散关系<beta>与“_1<alpha>”中的声子色散关系非常相似，这是由马氏体“_1”的单轴应力引起<gamma><gamma>的。从<gamma>10 K加热到A_s，声子色散关系在'_1中略有软化.在单轴应力作用下，母相（_1）中的声子色散曲线<beta>在布里渊区边界的q值（2/3）q_和附近略有软化<max>，马氏体相变被解释为孤子而不是声子的凝聚过程。马氏体相中的孪晶界是孤立子。在足够高的温度下，奥氏体相由动态孤子组成。需要一个有限的偏置场来稳定奥氏体中的动态孤子。预马氏体结构由与成分涨落相关的偏置场稳定的孤子组成。马氏体相由马氏体相变本身产生的偏置场作用下稳定的孤子组成。

Dependence of the phonon dispersion relation on the uniaxial stress of the transverse acoustic lattice waves, TA mode, both in the parent phase(<beta>_1) and in the martensitic phases (<gamma>'_1,<beta>''_1 and <alpha>'_1)of Cu-Al-Ni alloys were measured. The phonon dispersion relation in the martensite <gamma>'_1 was independent of the uniaxial stress up to 275 MPa. Furthermore, the phonon dispersion relations in the martensites <beta>''_1 and <alpha>'_1, which were induced by the uniaxial stress from the martensite <gamma>'_1, were very similar to that in <gamma>'_1. The phonon dispersion relation in <gamma>'_1 softened slightly by heating from 10 K to A_s. By applying uniaxial stress, the phonon dispersion curve in the parent phase (<beta>_1) softened slightly around q values of (2/3)q_<max> and of the Brillouin zone boundary.The martensitic transformation is interpreted as a condensation process of solitons instead of phonons. A twin boundary in the martensitic phase is a soliton. The asustenitic phase at sufficiently high temperature consists of dynamic solitons. A finite bias field is required to stabilize dynamic solitons in the austenite. The premartensitic structure consists of solitons stabilized by the bias field associated with the composition fluctuation. The martensitic phase consists of the solitons stabilized adiabatically by the bias field associated with the martensitic transformation itself.