Thermal rejuvenation in metallic glasses.
Thermal rejuvenation in metallic glasses.
复制标题
金属玻璃的热回春。
DOI：
10.1080/14686996.2017.1280369
复制
发表时间：
2017
影响因子：
5.5
通讯作者：
Ogata S
中科院分区：
文献类型：
--
作者：
Saida J;Yamada R;Wakeda M;Ogata S
通过热处理（即通过回复退火）对不同合金成分的金属玻璃进行了实验和理论研究。热再生后，观察到势能的增加，密度的降低，以及在局部结构的变化，以及机械软化。两个参数，一个有关的退火温度，Ta/Tg，和其他有关的恢复退火过程中的冷却速率，Vc/Vi，提出了评估的年轻化现象。使用这两个参数构建复壮图。由于金属玻璃的热历史在1.2Tg以上是重置的，并伴随着局部结构的变化，因此在退火过程中必须满足Ta/Tg ≥ 1.2的条件。在此温度范围内，随着二十面体短程有序的分解，玻璃态结构转变为更无序的状态。因此，取决于随后的淬火速率的新的玻璃态结构（复原）产生。Zr_（55）Al_（10）Ni_（55）Cu_（30）大块非晶合金在低温退火（Ta/Tg ~ 1.07）后快速冷却时也发生部分年轻化。这种行为可能起源于弱键合（松散堆积）区域的无序。该研究为通过控制非晶结构来改善非晶合金的力学性能提供了一条新的途径。
Structural rejuvenation in metallic glasses by a thermal process (i.e. through recovery annealing) was investigated experimentally and theoretically for various alloy compositions. An increase in the potential energy, a decrease in the density, and a change in the local structure as well as mechanical softening were observed after thermal rejuvenation. Two parameters, one related to the annealing temperature, T a/T g, and the other related to the cooling rate during the recovery annealing process, V c/V i, were proposed to evaluate the rejuvenation phenomena. A rejuvenation map was constructed using these two parameters. Since the thermal history of metallic glasses is reset above 1.2T g, accompanied by a change in the local structure, it is essential that the condition of T a/T g ≥ 1.2 is satisfied during annealing. The glassy structure transforms into a more disordered state with the decomposition of icosahedral short-range order within this temperature range. Therefore, a new glassy structure (rejuvenation) depending on the subsequent quenching rate is generated. Partial rejuvenation also occurs in a Zr55Al10Ni5Cu30 bulk metallic glass when annealing is performed at a low temperature (T a/T g ~ 1.07) followed by rapid cooling. This behavior probably originates from disordering in the weakly bonded (loosely packed) region. This study provides a novel approach to improving the mechanical properties of metallic glasses by controlling their glassy structure.