Solid solution additives

Diffusion Annealing. Mixed preformed carbides can be diffusion-annealed at temperatures giving solid solutions. Additives, such as Co, Ni, Fe, or Cr (0.5—1%) promote diffusion. 

Optical spectra showed a gradual shift of the onset with composition, as expected for a true solid solution. Additionally, the refractive index (and therefore the dielectric constant) increased gradually as the Se content increased, mirroring the larger dielectric constant of CdSe compared with CdS. 

In a given metal sample, grains with different chemical compositions may be found, as well as impurities in solid solution. Additional material, crystalline or amorphous, may also be found at the grain boundaries. Grain size and structure can be much influenced by thermal and mechanical treatments carried out during processing, as well as by the impurities , which are frequently present, either by accident or by design. 

Solid solution additives or dopants provide an effective approach for the fabrication, by sintering, of ceramics with high densities and controlled grain size, but as discussed in Chapter 9, the role of the dopant is not well understood. This gap in understanding limits the applicability of the approach. The major roles of the dopant and the parameters that control the effectiveness of a dopant in a given role form important issues in the solid solution additive approach. 

Whereas a limited amount of coarsening can serve to improve the micro-structural homogeneity during sintering, perhaps the most effective approach, described later in the chapter, involves the use of solid solution additives (dopants). 

As outlined in Chapter 9, the use of solid solution additives (also referred to as dopants) provides a very effective approach for the fabrication, by sintering, of... 

Brook RJ et al. (1985) Solid solution additives and the sintering of ceramics. Powder Metall 28 105-107... 

Manganese has a relatively low solubility in Al but improves its corrosion resistance in solid solution. Additions of manganese of up to 1% form the basis for an important series... 

Why does a freshly opened can of soda pop fizz, and why does fhe soda go flaf after a time To answer questions like these requires an understanding of the solubilities of gases. As discussed in this section, the effect of temperature on the solubility of gases is generally different from that on solid solutes. Additionally, the pressure of a gas strongly affects its solubility. 

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