Effects of carbon on the mechanical Properties & Microstructure of a Nb-based alloy

有时候，材料需要在高温下使用。例如，发电中的材料就是如此（例如，喷气发动机），其中该过程的效率与温度成比例。为了在高温下保持其强度，材料需要具有高熔点。这种“难熔”元素往往在周期表中处于过渡系列。目前人们相当感兴趣的一个很好的例子是铌。铌很容易获得，并且具有非常高的熔点。然而，它有两个主要缺点。它会氧化，因此需要保护，并且在高温下会失去强度。这个项目解决了第二个问题。最近发现，用碳强化铌不仅可以提高金属在高温下的强度，而且与大多数强化铌的方法不同，在低温下不会使其变脆。在拟议的工作中，我们将找出为什么和如何碳化物强化铌，但不会使其变脆，我们将模拟这两个过程。然后，我们将能够优化碳含量和合金的“热处理”方式。该国国防工业的未来取决于其理解和生产高温结构材料的能力，从而保持与其他先进制造业经济体的竞争力。

Sometimes materials need to be used very hot. This is true, for example, of materials in power generation (e.g.. a jet engine) where the efficiency of the process is proportional to the temperature. For a material to maintain its strength at high temperature it needs to have a high melting point. Such 'refractory' elements tend to be in the transition series in the periodic table. A good example of considerable current interest is niobium. Niobium is readily available and has a very highmelting point. It has two principal disadvantages, however. It oxidises, and therefore needs to be protected, and it loses its strength at high temperature. This project addresses the second of these problems.It has been found recently that reinforcing niobium with carbon not only improves the strength of the metal at high temperature, but, unlike most methods of strengthening niobium, does not make it brittle at low temperature.In the proposed work we will find out why and how carbides strengthen niobium, but do not make it brittle, and we will model both processes. We will then be able to optimise the level of carbon and the way in which the alloy is 'heat treated'.The future of this country's defence industry depends on its ability to understand and produce high temperature structural materials and thus stay competitive with other advanced manufacturing economies.