Chemical short-range order in amorphous CuTi prepared by mechanical alloying

• Published in: Journal of non-crystalline solids Vol. 175; no. 2; pp. 238 - 243
• Main Authors: Nakamura, Kuniyasu, Nagumo, Michihiko
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.10.1994; Elsevier
• Subjects: Amorphous semiconductors, metals, and alloys; Applied sciences; Condensed matter: structure, mechanical and thermal properties; Disordered solids; Exact sciences and technology; Metals. Metallurgy; Physics; Structure of solids and liquids; crystallography; Coordination number; Noncrystalline structure; Fourier transformation; Amorphous state; Experimental study; Mechanical alloying; EXAFS; Bond lengths; Binary alloys; Titanium alloys; Quantity ratio; Copper alloys; Short-range order; Transition element alloys
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/0022-3093(94)90016-7

Chemical short-range order (CSRO) in amorphous Cu x Ti 100− x samples prepared by mechanical alloying of elemental metal powders and mechanical grinding of intermetallic compounds has been examined by EXAFS. Curve fitting for the Fourier filtered first shell of the Fourier transform of EXAFS was conducted to determine the Cu coordination numbers. The Cowley CSRO parameter deduced from the coordination numbers shows a monotonic decrease with increasing Cu concentration. It is positive in the range of x < 68, and negative for x > 68. This behavior is quite different from the results of rapidly quenched CuTi amorphous alloys whose CSRO parameter is negative for all compositions. The ratio of coordination numbers of Cu and Ti atoms, N Cu/ N Ti, increases lineary for x < 57 and saturates to 2.1 for x > 57. The origin of CSRO in mechanical alloyed samples is probably due to inter-diffusion of Ti into Cu, while CSRO of samples derived from the liquid state is fixed during rapid quenching.