Development of Innovative Aluminum Powder Metallurgy (PM) Alloys Utilizing Hybrid Alloying Technology

该提案的重点是铝粉末冶金（PM）加工。 这是一种新兴的近净形金属成形技术，其中铝基粉末（和所需合金添加物的粉末形式）通过粉末压实、液相烧结和二次操作（例如热处理）的顺序直接被操纵成几何形状复杂的部件。近年来，铝粉末冶金主要通过开发具有高烧结密度（>99%）的新合金而稳步发展，并且相对于现在使用超过40年的过时的常规共混物，其环境机械性能有了显著改善。虽然新一代材料为铝粉末冶金加工开辟了许多新的应用，但也出现了新的挑战。最多产的是它们在烧结过程中不均匀收缩的倾向。由于强烈的致密化行为，它产生扭曲的烧结产品，并大大减少了近净形状的优势，铝PM是建立在。为了减轻变形的困境，申请人最近设计了一种被认为是“混合合金化”的概念，由此铝的烧结颗粒将通过添加少量的预合金化锆来强化。该元素在铝中具有缓慢的扩散速率并且形成Al 3 Zr颗粒的精细分布，所述Al 3 Zr颗粒是硬的、异常细（<20 nm）、热稳定的并且高度耐热粗化-这些属性使得铝化物颗粒能够在整个烧结循环中充当有效的强化特征。迄今为止，对该概念的研究仅限于单一基础合金和Zr的稀释浓度，但结果非常有希望，并意味着该技术存在更广泛的机会。因此，本提案的目的是扩大对混合合金化的研究，以最大限度地提高广泛商业应用的可能性。活动将解决一个增强的基本理解，化学精炼，混合合金在一系列合金中的使用，以及机械测试。

The focus of this proposal is aluminum powder metallurgy (PM) processing. This is an emerging near-net-shape metal forming technology wherein aluminum-based powders (and powdered forms of the desired alloying additions) are directly manipulated into geometrically complex components through a sequence of powder compaction, liquid phase sintering, and secondary operations such as heat treatment. Aluminum PM has advanced steadily in recent years principally through the development of new alloys that exhibit a high sintered density (>99%) and in turn, significant improvements in ambient mechanical properties relative to the out dated conventional blends now in use for over 40 years. While the next generation materials open many new applications for aluminum PM processing, new challenges have arisen as well. The most prolific is their propensity for non-uniform shrinkage during sintering. Coming as a result of the intense densification behaviour, it yields distorted sintered products and greatly diminishes the near-net-shape advantage upon which aluminum PM is built. To mitigate the distortion dilemma, the applicant recently designed a concept deemed "hybrid alloying" whereby the sintering particles of aluminum would be strengthened by the addition of a small amount of prealloyed zirconium. This element has a slow diffusion rate in aluminum and forms a refined distribution of Al3Zr particles that are hard, exceptionally fine ((<20nm), thermodynamically stable, and highly resistant to thermal coarsening - attributes that enable the aluminide particles to act as efficient strengthening features throughout the complete sintering cycle. Research on the concept has been restricted to a single base alloy and dilute concentrations of Zr to date yet the results are highly promising and imply that a much broader scope of opportunities exists for the technique. Thus, the objective of this proposal is to expand research on hybrid alloying to maximize the likelihood of widespread commercial adaptation. Activities will address an enhanced fundamental understanding, chemical refinements, the use of hybrid alloying in an array of alloys, and mechanical testing.