Fe2U, as the right hand border. Intermetallic compounds form when integer atom ratios of the two components form a crystallographic structure of high stability. These compounds often have high melting points, as does Fe2U, thus enabling it to serve as the second "wall" of the eutectic field. The Fe-rich portion of the Fe-U phase diagram consists solely of two-phase regions (except for the liquid). The two-phase regions contain various combinations of the three phases of pure iron and the liquid or Fe2U.
The diagram of Fig. 8.14 contains another eutectic point at 85.7 mole percent U and 725oC. This eutectic region is bounded on the left by Fe2U and on the right by another intermetallic compound, FeU6. It is exactly like the Au-Si phase diagram.
Pure uranium exhibits three crystal forms: aU stable up to 660oC, PU from 660oC to 776oC, and yU from 776oC to the melting point. Contrary to the total insolubility of U in solid Fe, solid uranium dissolves small amounts of iron in each of the three crystal structures. The three zones labeled aU, PU and yU in Fig. 8.14 are single-phase zones resembling the P region in Fig. 8.10. The three U-rich solutions appear in adjacent two-phase regions along with the liquid or with FeU6. These regions are analogous to the two-phase zones in the Fe-rich portion of the diagram.
Additional practice in identifying the species and phases present in regions of phase diagrams is provided in problems 8.7, 8.12, 8.13, 8.14 and 8.20. Problem 8.21 shows how to describe the change in the relative amounts and the compositions of phases that appear as a binary system is cooled from the liquid state.
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Do we really want the one thing that gives us its resources unconditionally to suffer even more than it is suffering now? Nature, is a part of our being from the earliest human days. We respect Nature and it gives us its bounty, but in the recent past greedy money hungry corporations have made us all so destructive, so wasteful.