Titanium silicide properties

Titanium Silicides. The titanium—silicon system includes Ti Si, Ti Si, TiSi, and TiSi (154). Physical properties are summarized in Table 18. Direct synthesis by heating the elements in vacuo or in a protective atmosphere is possible. In the latter case, it is convenient to use titanium hydride instead of titanium metal. Other preparative methods include high temperature electrolysis of molten salt baths containing titanium dioxide and alkalifluorosiUcate (155) reaction of TiCl, SiCl, and H2 at ca 1150°C, using appropriate reactant quantities for both TiSi and TiSi2 (156) and, for Ti Si, reaction between titanium dioxide and calcium siUcide at ca 1200°C, followed by dissolution of excess lime and calcium siUcate in acetic acid. 

The theoretical studies " have been focused on TiSi2. Some attempts, with use of high-symmetry crystal structures, have been made to understand some of the other titanium silicides. This paper deals vith Ti,5Si.3. Because of the crucial interplay between structure and bonding we have studied the proposed stable low-symmetry crystal structure. This will give a better picture of the electronic structure and the bonding properties in this system. An investigation of seven members in the Ti-Si system will be presented in a future publication. ... 

Other interesting directions are hardening with intermetallics, quasi-crystals, borides, silicides, discrete fibres, creation of natural composites. Conscious regulation of structure and properties of such materials requires studying phase equlibria in multi-component systems, in particular on the basis of light metals like aluminum, magnesium, titanium. The important direction is also a creation of specially organized porous structures. To some extent these directions are presented in a number of papers of the present book. 

Key words Titanium in-situ composites, discontinuous reinforcement, silicide reinforcement, boride reinforcement, mixed silicide-boride reinforcement, ductile reinforcement, microstructure, a -phase, (3-phase, mechanical properties, fracture mechanisms. 

In order to take advantage of the superior properties of these refractory silicides in combination with a ductile titanium matrix particle and fiber reinforced composites based on a-Ti-Si-(Al) have been developed. Two different processing routes have been performed ... 

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