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铜金二元系中超结构的形成与点阵间隔的变迁

陆学善 梁敬魁

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铜金二元系中超结构的形成与点阵间隔的变迁

陆学善, 梁敬魁

THE SUPERLATTICE FORMATION AND LATTICE SPACING CHANGES IN COPPER-GOLD ALLOYS

LU HSUEH-SHAN, LIANG CHING-KWEI
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  • 本文用X射线衍射的方法全面地研究了Cu-Au二元系合金经不同时间(一个月、三个月、六个月、一年)熟炼后缓冷到室温,以及在300℃和600℃淬炼后的物相与相转变过程;精确地测定了点阵间隔,以研究其随成份和热处理的变迁;探讨了长周期超结构的堆垜周期同成份和温度的关系;并用保持不同热处理时间后淬炼的方法来研究等原子成份处的有序化过程。在上述的热处理条件下,整个二元系共出现了六种不同的相:α1是Au在Cu中的固溶体,α′1是相当于Cu3Au的超结构,α2是Cu在Au中的固溶体,α′2是相当于CuAu3的超结构,k是相当于CuAuⅠ的超结构,k′是相当于CuAuⅡ的超结构。值得注意的是,随着热处理时间的加长,有序区逐渐扩大,二相区逐渐缩小,在一年缓冷的合金,二相区几乎完全消失。因此作者认为:Cu-Au系的二相共存是处于介稳状态,以α′2相而论,最清晰的超结构线并不出现在化学计量成份而在68at.%Au。在等原子成份两边所出现的k′相,当合金经一年熟炼之后,一部分又变成了k相,在等原子成份处,k相和k′相的最高转变温度都并不恰好在等原子成份,而在于或小于49at.%Au。点阵间隔的量度表明:基本单胞平均点阵间隔同成份的关系是正偏离Vegard定律的连续曲线。在α和α′相区内,α值随Au含量而递增。在Au含量小于等原子成份的k′相区内,α值随Au含量而递增,c值则反而递减,同时c/α愈来愈偏离1。而在Au含量大于等原子成份的k′相区内,α值随Au含量的增加而缓慢地下降,c值却随之急速上升,同时c/α愈来愈趋向于1。当k′相转变为k相或k相转变为k′相时,α和c均发生突然的跃变。以热处理时间对点阵间隔的关系而论,在α,α′及k相区内,凡相状态不随熟炼时间而变的部分,点阵间隔在实验条件的范围内是恒定的。在α′2相区内,从无序相转变到有序相时发生点阵间隔的明显下降,在k′相区内,则凡Au含量小于等原子成份的合金,α值随处理时间而递增,c则递减;而Au含量大于等原子成份的合金,α和c都随处理时间的加长而递减。但在所有k′相区内,同一成份合金的基本单胞体积都随处理时间的增加而减小,作者因此认为:应该把基本单胞的体积作为有序度的普通量度。本文详尽地讨论了k′结构超结构线的指数出现规律和它同k结构超结构线指数的对应关系。从在k到k′的变化中劈裂成双线的线间距离准确地测定了k′结构的堆垜周期,堆垜周期随成份的变化是连续的。凡合金离理想成份愈远,堆垜周期愈大。同一成份的合金,温度愈高则堆垜周期愈大。堆垜周期可以为奇数,也可以为非整数。在介稳二相区内,非但点阵间隔随成份而变,而且k′相的堆垜周期也随成份而变。二相1963年8月曾在长春市举行的第一届全国物质结构学术会议上宣读过。共存实际上是由一种成份的两种结构形式所组成。本文纯粹从热力学的关系证明了Cu-Au二元系的有序、无序变化是二级相交。
    A thorough investigation of the Cu-Au system has been taken by means of X-ray diffraction studies. Alloys were annealed at appropriate temperatures for different periods (one month, three months, six months and one year) and slowly cooled down to room temperature, or quenched at 300° and 600℃, with the purpose to elucidate the phases and the phase transformations that might occur. Lattice parameters were accurately determined in order to study their variations with compositions and heattreatments. The stacking periods of the ordered structures with long periods were investigated, particularly in their relations to compositions and temperatures, and by means of quenching alloys after having been annealed for various periods of time, the ordering process near the equiatomic composition was studied. Under the conditions of heattreatment mentioned above, the entire system consists of six different phases: α1 is the primary solid solution of Au in Cu, α′1 the superstructure corresponding to Cu3Au, α2 the primary solid solution of Cu in Au, α′2 the superstructure corresponding to CuAu3, k the superstructure corresponding to CuAu I, and k′ the superstructure corresponding to CuAu II. The most noteworthy is the fact that with the increase of the period of annealing, the ordered regions extend gradually, while the two-phase regions gradually narrow down, and in the slowly cooled alloys after one year's treatment, the two-phase regions almost disappear. This leads the authors to conceive that the two-phase coexistence in the Cu-Au system is in a state of metastable equilibrium. As for the α′2 phase, the most clear superlattice lines appear not at the stoichiometric composition but at 68 at.% Au. The k′ phases which appear at both sides of the equiatomic composition are partially transformed into k phases after the alloys being treated for one year. By the equiatomic composition, both the maximum transformation temperatures of the k phase and the k′ phase are not exactly at the equiatomic composition but at 49 at.% Au or even less.The measurement of lattice spacings shows that: the relation between the mean lattice spacings of the fundamental unit cells and the compositions is a continuous curve indicating positive deviation from Vegard's law. In the a and a′ regions, a increases with the Au content. In the k′ regions, for alloys where the Au contents are less than that in the equiatomic composition, a increases with the Au content while c decreases, and meanwhile c/a deviates gradually from 1 ; and for alloys where the Au contents are more than that in the equiatomic composition, a decreases gradually with the increase of the Au content, while c increases abruptly, and c/a gradually approaches 1. At the compositions where k′ transforms into k or vice versa, both a and c undergo abrupt changes.The influence of the period of annealing to lattice spacings has been fully considered. The lattice spacings in those parts of the phase regions wherein the phases do not change with the heattreatment are practically unchanged within the experimental conditions cited above. In the α′2 region, the transformation from disorder to order causes sharp drop in the lattice spacing. In the k regions, for alloys where the Au contents are less than that in the equiatomic composition, a increases with the period of annealing; and for alloys where the Au contents are more than that in the equiatomic composition, both a and c decrease with the increase of the period of annealing. But in all k regions, the volume of the fundamental unit cell decreases with the increase of the period of annealing. The authors are therefore of the opinion that the volume of the fundamental unit cell should be taken as a general measure of the degree of order.The law governing the indices of the superlattice lines present in the k′ structures has been discussed in details as well as their correspondence to those present in the k structure. The stacking periods in the k′ structures have been accurately determined by measuring the distances between the doublets arising from the splitting of the k superlattice lines as k is transformed into k′. The variation of stacking periods with compositions is continuous. The farther the alloy is from the ideal composition, the longer is the stacking period. And for the same alloy, the higher the temperature, the longer the stacking period. The stacking period may be odd, and may be a non-integer.In the metastable two-phase regions, not only the lattice parameters, but also the stacking periods of the k′ phase vary with compositions. The two-phase coexistence is composed really of two structural forms with the same composition. Purely from ther-modynamic considerations, it has been shown that the order-disorder transformations in the Cu-Au system are transformations of the second order.
  • [1]
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    [20] 徐锡申. 体心立方晶二元合金超点阵理论. 物理学报, 1956, 12(6): 528-549. doi: 10.7498/aps.12.528
计量
  • 文章访问数:  7218
  • PDF下载量:  527
  • 被引次数: 0
出版历程
  • 收稿日期:  1965-10-29
  • 刊出日期:  1966-03-05

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