Acta Phys. -Chim. Sin. ›› 2001, Vol. 17 ›› Issue (08): 708-712.doi: 10.3866/PKU.WHXB20010808

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MediumRange Order Structure Clusters in Cu12%Al Elloys Melt

Pan Xue-Min;Bian Xiu-Fang;Qin Jing-Yu;Wang Wei-Min   

  1. Key Laboratory of Liquid Structure and Heredity of Materials, Education of Ministry, Shandong University, Jinan 250061
  • Received:2001-02-12 Revised:2001-03-20 Published:2001-08-15
  • Contact: Pan Xue-Min

Abstract: Using Xray diffraction, the structure factors of molten Cu12%(mass fraction)Al alloys and pure copper have been investigated. Distinct prepeak(the prepeak occurs at values of scattering vector Q=18.5 nm-1) has been found in the structure factor of Cu12%Al alloys melt at 1250 ℃. The prepeak in the liquid alloy increases with decreasing temperature. The prepeak is a sign of mediumrange order. Rapid solidified ribbons prepared by the single roller meltspinning technique have been investigated with Xray scattering. The phase in the ribbons is Cu3Al with superstructure. The structural unit size of mediumrange order clusters in liquid equals to intercrystal face distance d111 of Cu3Al. According to the nearest neighbor distance and coordination number, obtained from the pair correlation function, and basic unit model of cluster, the length of cubic edge can be calculated, which meets the parameter of the crystalline structure given by literature. So it is speculated that there are DO3 structure clusters in the liquid Cu12%Al alloy. This stable mediumrange order can exist up to nearly 200 ℃ above liquidus and the structural correlation length increases with decreasing temperature.

Key words: Cu-12 %Al alloy liquid structure, Structure factor, Prepeak, X-ray diffraction