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合金AgAuZn2具有一个与郝斯勒合金同晶型结构的β″相,这个β″相存在于一个相当广阔的成分范围里。事实上,β″相就是β′有序结构的超结构。伴随着,β″结构的形成晶格发生突然的收缩。关于Ag-Au替换对于原子分布的影响,也作了系统的观察。在Ag-Au替换过程中,Au和Ag的替换或多或少是无规律性的,但Zn原子则仍保持它们的适宜位置,而不受到影响。当成分偏离于理想化学式AgAuZn2时,有序度的减小不仅仅是由于化学成分的乖异,而且Ag-An替换也产生了一些无序的排列。高温观察的结果指出:Ag多合金的β′-β转变温度随着Au含量的增加而升高,而β相只能在高温度存在。少量的Au大大地提高了由淬炼而得到的β′相的稳定度。但是Au多的合金无论是在室温和高温都是具有β′结构的。A β″ superlattice structure, with the ideal stoichiometrical formula AgAuZn2 and isoinorphous with that of Heusler alloys, has been found existing over a quite wide range of composition. It is, in fact, a superstructure of the β′ ordered structure. Its formation is accompanied by a sudden lattice contraction. The effect of gradual substitution of Ag by An on the atomic distribution has been stndied systematically. It is shown that the Au atoms introduced simply replace the Ag atoms more or less in a random manner, the positions of Zn atoms not being affected. Tho decrease of the degree of order as deviating from the stoichiometrical formula is not merely due to the deviation from the ideal chemical composition; some disordering among the Ag and Au atoms also occurs. High temperature investigation of Ag-rieh alloys shows that the temperature of β′-β transformation increases with Au content and that the β-phase structure exists only at high temperatures. The presence of even a minute amount of Au stablizes the β′ structure obtained by quenching very remarkably. On the other hand, the β′ structure of Au-rich alloys persists from room temperature probably to the melting point.
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