ROW: Mechanical Alloying of Nb3Al Intermetallics

本研究的目的是研究元素粉末机械合金化制备纳米晶Nb3A1的可行性。之所以选择Nb3A1金属间化合物，是因为它在结构铝化物中具有最高的耐温性能和超导体的高电流密度特性。机械合金化对合成Nb3A1金属间化合物的吸引力在于它能够通过固态加工制造出具有控制显微组织的合金。这对Nb和A1尤其重要，它们在熔点和密度上有很大的差异，从而导致传统的熔化技术困难、危险和不可控。此外，机械合金化有可能获得非常细的晶粒尺寸，最终在纳米范围内，这将大大超过传统加工的金属间化合物的性能。纳米结构加工的主要优点——超塑性——对于通常以完全缺乏延展性和可成形性而闻名的金属间化合物来说更有价值。因此，Nb3A1作为一种非常耐高温、密度相对较低和抗氧化的材料的优点可以充分用于工业和航空航天应用。这些合金在超导和航空航天/结构应用中都非常有趣，如果它们的延展性可以得到改善，它们可以广泛应用。

The purpose of the research is to study the feasibility of nanocrystalline Nb3A1 formation by mechanically alloying elemental powders. Nb3A1 intermetallic was chosen for its highest temperature capability among structural aluminides as well as for its high current density property as a superconductor. The appeal of mechanical alloying for the synthesis of Nb3A1 intermetallics stems from its capability to make alloys with controlled microstructure via solid-state processing. This is particularly important for Nb and A1 which have large differences in melting points and densities thereby causing conventional melting techniques to be difficult, hazardous and less controllable. In addition, mechanical alloying has the potential of obtaining very fine grain sizes, eventually in the nanometer range that hold the promise for properties greatly exceeding those of conventionally processed intermetallic compounds. The main benefit of nanostructure processing -superplasticity- is more rewarding for intermetallics that are usually known for their complete lack of ductility and formability. Consequently, the benefits of Nb3A1 as a very high temperature resistant, relatively less dense and oxidation resistant material may be fully used in industrial and aerospace applications. These alloys are extremely interesting in both superconducting and in aerospace/structural applications and could be widely used if their ductility could be improved.