Thermal Stability of Nonequilibrium Alloys Produced by Vapor quenching

在溅射沉积过程中，高能量的蒸气溶液凝结在冷基体上，得到了范围广泛、种类繁多的非平衡合金。虽然这些非平衡合金显示出优异的磁性和催化性能，但它们是热不稳定的。为了提高非平衡态合金的热稳定性，研究了热处理对非平衡态合金的组织和物理性能的影响：差示扫描量热法和红外热像炉退火前后的x射线衍射图、磁化和穆斯堡尔光谱的测量。我们得到了以下结果。(1)非平衡态二元结晶Fe-Cu和Fe-Ag合金和三元非晶态Fe-Cu- ag合金具有矫顽力小于1 oe、磁通密度高的软磁特性。非平衡态Fe-Cu和Fe-Ag合金在300℃以上发生相分离，而非平衡态Fe-Cu- ag合金在130℃以上转变为bcc和fcc相。(2)非平衡态Fe-Ti合金具有良好的储氢和滤氢性能。由于它们的热稳定性高达700摄氏度左右，因此它们将被用作工业材料。(3)在非平衡Fe-Pd合金,铁原子的磁矩是扩大和软磁性特征观察,也就是说,矫顽力小于10 Oe的好状态,所以就约5 Oe通过退火低于300 C。这些合金进行相位差300度以上,然而,他们表现出非常有趣的磁性特征在500 C退火后,即矫顽力大约是500 Oe和磁通密度大约是18 kOe,与钴镍磁性记录介质的性能相当或更佳。目前，我们正在研究非平衡态合金的EXAFS光谱和XPS光谱及其退火后的变化。

In sputter-deposition process a high energy vapor solution is condenced onto a cold substate and a wide range and a wide variety of nonequilibrium alloys have been obtained. Although these nonequilibrium alloys reveal excellent magnetic and catalytic properties, they are thermally unstable. In order to improve their thermal stability we have studied effects of heat treatments on the structure and physical properties of nonequilibrium alloys: differential scanning calorimetry and measurements of X-ray diffraction patterns, magnetization and Mossbauer spectra before and after annealing in an infra-red image furnace. We have obtained the following results.(1) Nonequilibrium binary crystalline Fe-Cu and Fe-Ag alloys and ternary amorphous Fe-Cu-Ag alloys show a soft magnetic characteristic, i.e., the coercive force less than 1 oe and high magnetic flux density. However, the nonequilibrium bcc and fcc Fe-Cu and Fe-Ag alloys undergo a phase separation above 300 C, while the amorphous Fe-Cu-Ag alloys transform to bcc and fcc phases above 130 C.(2) Amorphous Fe-Ti alloys are good hydrogen storage and good hidrogen filters. Since they are thermally stable up to about 700 C, they will be used as industrial materials.(3) In nonequilibrium Fe-Pd alloys, the magnetic moment of Fe atoms are enlarged and a soft magnetic characteristic is observed, i.e., the coercive force is less than 10 Oe in the as-prepared state and it becomes about 5 Oe by annealing below 300 C. These alloys undergo a phase separation above 300 C, however, they show very interesting magnetic characteristics aFter annealing at 500 C, i.e., the coercive force is about 500 Oe and the magnetic flux density is about 18 kOe, being comparable to or getter than those of Co-Ni magnetic recording media.Now, we are studying EXAFS spectra and XPS spectra of the nonequilibrium alloys and their variation by annealing.