Diffusion Rates of Components in Metal-Silicides Depending on Atomic Number of Refractory Metal Component

Abstract

Interdiffusion studies conducted in group IVB, VB and VIB metal-silicon systems are discussed in detail to show a pattern in the change of diffusion coefficients with the change in atomic number of the refractory metal (M) component. MSi 2 and M 5 Si 3 phases are considered for these discussions. It is shown that integrated diffusion coefficients increase with the increase in atomic number of the refractory component when the data are plotted with respect to the melting point normalized annealing temperature. This indicates the increase in overall defect concentration facilitating the diffusion of components. This is found to be true in both the phases. Additionally, the estimated ratios of tracer diffusion coefficients indicate the change in concentration of antisite defects in certain manner with the change in atomic number of the refractory components.

High-Pressure and High-Temperature Synthesis and In Situ High-Pressure Synchrotron X-ray Diffraction Study of HfSi2

“…HfSi 2 with a layered structure (space group Cmcm) is structurally isotypic with many transition-metal disilicides and digermanides, such as ZrSi 2 , ZrGe 2 , and HfGe 2 . 24,39,40 The refined lattice parameters at ambient conditions are a = 3.668 ± 0.001 Å, b = 14.534 ± 0.004 Å, and c = 3.639 ± 0.001 Å, yielding a unit cell volume of 194.0 ± 0.1 Å 3 , which is consistent with the result from previous studies on powdered samples 41 and slightly smaller than the reported value for a single crystal 40 (Table 1).…”

Interface reactions of magnetron sputtered Si-based dual layer coating systems as oxidation protection for Mo-Si-Ti alloys

“…16 c)) triggered by the inward diffusion of the Si to the Mo-Si interlayer. Since Si has a high diffusion rate in Mo, it diffuses towards the substrate alloys despite the Si oxide formation which leads to Kirkendall pores [47,48]. In the remaining area of the Si top layer of CS1, uniformly distributed porosities can also be seen after 10 hours, which agglomerate with increasing oxidation.…”

Fabrication and Thermoelectric Characterization of Transition Metal Silicide-Based Composite Thermocouples

“…Since the melting point of ZrSi is close to the sintering temperature, it could result in partial melting during the sintering hold at temperature, and thus, a slight formation of the silicon (Si) phase as detected by XRD. The presence of ZrSi and Si phases along with the ZrSi 2 phase was similarly found in the Zr/Si diffusion couple after high-temperature annealing at 1200 °C [20]. Furthermore, Rietveld refinement results in the authors’ previous study [14] demonstrated that ~20.2 vol % of a secondary Mo 5 Si 3 phase formed in the [90–10] MoSi 2 -Al 2 O 3 composite after sintering.…”