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

这项提案的重点是铝粉冶金(PM)加工。这是一种新兴的近净形状金属成形技术，其中铝基粉末(和所需合金化添加剂的粉末形式)通过一系列粉末压制、液态烧结和二次操作(如热处理)被直接操纵成几何复杂的组件。铝粉末冶金近年来稳步发展，主要是通过开发具有高烧结密度(&gt；99%)的新合金，以及与使用了40多年的过时的传统混合物相比，环境机械性能的显著改善。尽管新一代材料为铝粉末冶金加工开辟了许多新的应用领域，但也出现了新的挑战。最多产的是它们在烧结过程中收缩不均匀的倾向。由于强烈的致密化行为，它产生了扭曲的烧结产品，并极大地削弱了铝粉末冶金所基于的近净形状优势。为了缓解扭曲困境，申请人最近设计了一种被认为是“混合合金化”的概念，即通过添加少量预合金化的锆来强化铝的烧结颗粒。这种元素在铝中的扩散速度很慢，并形成了Al3Zr颗粒的精细分布，这些颗粒坚硬、异常细小(&lt；20 nm)、热力学稳定，并且高度抵抗热粗化-这些属性使铝化物颗粒能够在整个烧结循环中作为有效的强化特征。到目前为止，对这一概念的研究仅限于单一基合金和稀锆浓度，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，这项提议的目标是扩大对混合合金化的研究，以最大限度地扩大广泛的商业适应的可能性。活动将涉及加强基本了解、化学改进、在一系列合金中使用混合合金化以及机械测试。

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.