Are there carbon-silicon alloys?

Both carbon and silicon expose a lot of metallic properties like metallic lustre, electrical and heat conductivity, etc, so often considered metalloids. The both form alloys with other metals such as iron.


On the other hand, the usual silicon carbide is not an alloy at all. It is tranparent, electrical insulator etc. 


I wonder whether there is a different carbon-silicon compound that has more metallic properties?


Carbon (graphite):


![enter image description here](https://i.stack.imgur.com/WHMwu.jpg)
![enter image description here](https://i.stack.imgur.com/q4F2j.jpg)
![enter image description here](https://i.stack.imgur.com/WK5sq.jpg)


Silicon:


![enter image description here](https://i.stack.imgur.com/EEGmz.jpg)
![enter image description here](https://i.stack.imgur.com/xlLQu.png)


Silicon carbide:


![enter image description here](https://i.stack.imgur.com/BMH2G.jpg)


![enter image description here](https://i.stack.imgur.com/Qv82B.jpg)




[Here](http://www.ioffe.ru/SVA/NSM/Semicond/SiC/thermal.html) you can find a phase diagram for $\ce{Si/C}$ system. It does not have zones with homogeneous non-stoichiometric solids. So, there is not thermodynamically stable Si/C isomorphic alloys. However, since the liquid likely to be homogeneous, it is likely for fast cooled liquid to form amorphous alloys. Indeed, google search provides plenty of links for [amorphous $\ce{Si/C}$ alloys](https://www.google.ru/webhp?q=amorphous%20silicon-carbon%20alloys#newwindow=1&safe=off&q=amorphous%20silicon-carbon%20alloys). However, it is also possible for cooling liquid to form polycrystalline alloy, say, with $\ce{SiC}$ and $\ce{C}$ grains, similar to pig iron.


 10

One might consider [reaction-bonded silicon carbide](https://www.azom.com/amp/article.aspx?ArticleID=147)(see also Ref. [1](https://doi.org/10.1016/j.jeurceramsoc.2018.04.055)), which is essentially a composite of silicon carbide and elemental silicon, sometimes also containing graphite for sealing applications. To make reaction-bonded silicon carbide, a porous part containing silicon carbide and carbon is permeated with molten silicon. The reaction between the silicon and the carbon binds the material, as does leftover molten silicon which solidifies as it cools. The resulting material is lightweight and has a favorable properties for a variety of high-temperature and mechanical applications, including some cases (such as burner tubes in furnaces) where it competes with metallic alloys.


**Reference**


1. Sebastian Meyers, Lien De Leersnijder, Jef Vleugels, Jean-Pierre Kruth (2018).
"Direct laser sintering of reaction bonded silicon carbide with low residual silicon content:.
*Journal of the European Ceramic Society*,
**38**(11),
2018,
Pages 3709-3717,
ISSN 0955-2219,
<https://doi.org/10.1016/j.jeurceramsoc.2018.04.055>.


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