Solid state amorphization in the Co-Ti system

• Published in: Thin solid films Vol. 345; no. 2; pp. 319 - 329
• Main Authors: BENEDICTUS, R, TRAEHOLT, C, BÖTTGER, A, MITTEMEIJER, E. J
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier Science 21-05-1999
• Subjects: Applied sciences; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Low-dimensional structures (superlattices, quantum well structures, multilayers): structure, and nonelectronic properties; Metals. Metallurgy; Physics; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Intermetallic compounds; Crystal orientation; Amorphization; Theoretical study; XRD; Solid-solid interfaces; Cobalt; Titanium base alloys; Thin films; Binary alloys; Multilayers; Thermodynamic model; Transition elements; Ordering; Titanium; Kinetics; Cobalt alloys; Transition element alloys
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/S0040-6090(98)01419-9

Application of a thermodynamic model shows that in the crystalline Co-crystalline Ti system amorphization can occur both along the Co-Ti interface and along (high angle) grain boundaries in the Co and Ti sublayers. The model also predicts a preferred composition and a certain limiting thickness for the amorphous product layer at the interface. These predictions are largely in agreement with experimental data obtained for Co-Ti multilayers at temperatures in the range 523-583 K. A parabolic growth behaviour is observed for the amorphous phase, suggesting diffusion controlled growth. The activation energy for the diffusion in the amorphous phase is (160 plus or minus 8) kJ/mol. Annealing the specimen for a relatively long time or at a relatively high temperature, causes the amorphous phase to crystallize into an intermetallic phase with a CsCl-type structure and an average composition of Co sub(40)Ti sub(60). The orientation relationship between the crystalline Co layers and the crystalline Co sub(40)Ti sub(60) phase was found to be Co(11 1 )/ /Co sub(40)Ti sub(60)(1 10) and Co[110]//Co sub(40)Ti sub(60)[111] or Co[110]//Co sub(40)Ti sub(60)[001].