Function Of Chromium Content Research Articles

Sputtered Silicon–Chromium Resistive Films

The resistivity, temperature coefficient of resistance (TCR), and structure of annealed films deposited by de diode sputtering have been studied as a function of chromium content over the range 17–33 at.% Cr. The resistivity decreases from 0.1 to 0.001 Ω cm and the TCR changes from −1500 to +500 ppm/°C with increasing Cr content. Films containing about 27 at.% Cr had the lowest TCR. Films deposited at a cathode potential of 10 kV have a more positive TCR for the same resistivity than films sputtered at 2.5 kV. Electron micrographs showed the latter films to have a coarser structure—due either to a larger grain size (150 Ă compared to 50 Å) or to a clumping of grains. Electron diffraction patterns indicated a nearly amorphous film; CrSi2 was the only identifiable phase. The average drift of 50 μm-wide resistors (1 to 25 kΩ/square) during 1800 h at 200 °C (no load) or 125 °C (50 V dc) was ±0.5% after an initial 200 h aging under the same conditions.

Magnetic Phase Equilibrium in Cr-Substituted CaFe2O4

The structure of CaFe2O4 has orthorhombic symmetry (space group Pnam-D2h16) and is characterized by Fe–O–Fe–O chains within which the Fe–O–Fe bond angle is ∼130°. These chains are cross linked by means of Fe–O–Fe bonds in which the angle is ∼99°. The compounds (Ca (CrxFe1−x)2O4, with 0≤x≤0.5, have been found, by means of neutron measurements, to exhibit two magnetic structures in each of which the chains are internally antiferromagnetic, with spins alternating +−+− along the chain. In one structure the chains are linked ferromagnetically through the 99° bonds, with magnetic symmetry Pn′a′m, and in the second they are antiferromagnetically coupled, corresponding to the space group Pna′m. A phase diagram has been constructed showing both single-phase regions and a region in which the two phases exist in equilibrium. Transition temperatures as well as the temperature dependence of magnetic moments and phase concentration have been determined as a function of chromium content. The problem posed by the coexistence, at equilibrium, of two magnetic phases belonging to a single-crystal structure will be discussed.

Extrusion effect on 61S aluminium alloy

A study was made on the effects of extrusion conditions, heat-treating temperature and chromium content on the tensile strength of the extruded 61S. A extrusion effect was observed when billets were extruded at the temperature higher than 400°C, and then the tensile strength increased with the elevation of the billet temperature. The critical tempertaure of the billet which produces the extrusion effect is a function of chromium content, and the temperature becomes lower according with the increase in chromium content. The critical chromium content which srises the extrusion effect is about 0.3 percent, and the tensile strength is nearly constant regardless of the billet temperature when chromium is less than the critivcal content. The extrusion effect was observed markedly when the billets were extruded without soaking. Both the solution heat-treating temperature and the extrusion ratio affect on the extrusion effect. It is obvious that the above mentioned extraordinary strengthening characteristic is connected with some factors governing the recrystallization temperature of extruded 61S.We discussed the above results and suggested that the extrusion effect may be resulted from the overlap of two effect i. e. substructure hardening effect and the strengthening effect resulted from the interaction between the edge dislocations at subboundaries and the solute atoms in G. P. zones formed at subboundaries in low temperature aging, and that a press effect can be explained rather by the above mentioned mechanism than the strengthening effects depended on texture and anisotropoic hardening.