Chromium silicides

Copper—chromium and copper—nickel—silicon—chromium alloys are also precipitation hardenable. The precipitates are nickel sdicides, chromium silicides, and elemental chromium. If conductivity is critical, the chromium—silicon ratio should be held at 10 1 so that appreciable amounts of either element are not left in soHd solution in the copper after aging. Lithium can be used as a deoxidizer in copper alloys when conductivity is important. For a discussion of the principle of age- or precipitation-hardening copper alloys, see Copperalloys,wrought copperalloys. 

The results of two studies of silicide films are presented in Tables IV and V. For the results shown in Table IV, molybdenum silicides were deposited on vitreous carbon disks. One set was stripped with base (2 N NaOH), and the other set was stripped with acid (HF-HN03-H20, 1 1 10). The study of chromium silicides (Table V) gave similar results. 

PIBT of Cr-implanted Si results in full crystallization of the Si layer at fluencies up to MO cm. Precipitates of chromium silicide with semiconductor type of absorption (probably CrSi2) are formed at the depth more than 20 nm by data of optical and Raman spectroscopy. The increase of implantation fluence up to 6-1 o cm results in an increase of the precipitate density up to 6T0 cm increase of roughness (up to 6.9 nm). The subsequent Si growth was non-epitaxial. 

SiO as Fe. Franciosi fit al. (71) demonstrated that Si-Cr interface formation at room temperature results in reacted phases that differ from both bulk chromium silicide and a Sl-rlch chromium silicide. 

The thermodynamic characteristics of the chromium silicides Cr3Si, Cr5Si3, CrSi, and CrSi2 have been determined electrochemically. ... 

K spectra of silicon were obtained in pure silicon, CtSi, and CrSij. The identity of Kg of silicon in pure silicon, CrSi, and CrSij can be assumed from a comparison of Kg of pure silicon and chromium silicides. The semiconducting properties of chromium disilicide may be due to the presence of a partially covalent bond. A comparison of the structures of CrSi and CrSi2 indicates the identity of silicon atoms in the first coordination sphere. 

The participation of the outer electrons in the chemical bonds, accompanied by a change in the spatial electron density distribution, has an effect on the position of the K level. As Karal nik [6] showed, the level displacement caused by a change in the screening of the nucleus by the valence electrons is as high as 1 eV. Our investigation of the position of the K line of silicon in the chromium silicides showed that, within the limits of experimental error, it coincides with its position in the pure element. 

Ramos AR, Conde O, Paszti F, Battistig G, Vazsonyi E, da Silva MR, da Silva MF, Soares JC (2000) Ion beam synthesis of chromium silicide on porous silicon. Nuclear Instrum Methods Phys Res B 161-163 926-930... 

Chromium Silicides. Several compounds exist e.g. CrjSi, Cr2Si, CrSi, Cr3Si2 and CrSi2- The m.p. varies from approx. 1550 C for CrSi and CrSi2 to approx. 1700°C for Cr3Si. Hardness varies from 76-89 Rockwell A. These silicides resist oxidation up to about 1000°C they have good resistance to thermal shock but low resistance to impact. 

In conclusion, the effect of ion bombardment on amorphous Cr-O-Si layers is manifested in major surface chemical and short-range structural changes. Ar bombardment can be used to create chromium silicide clusters. To avoid such ion-beam-induced transformations, depth profiling by wet chemical etching may be preferable. 

---