Collaborative Research: Formation and Stability of Eutectic Nanostructures in Laser-Irradiated Particle Suspensions

合作研究：激光照射颗粒悬浮液中共晶纳米结构的形成和稳定性

基本信息

批准号：
1663085
负责人：
J. Floro
金额：
$ 37.66万
依托单位：
University of Virginia Main Campus
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2017
资助国家：
美国
起止时间：
2017-10-01 至 2021-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1663085&HistoricalAwards=false
关键词：
Collaborative Research Formation Stability Eutectic

项目摘要

Powder metallurgy, in which complex parts are made by fusing together a metal powder, has a large economic footprint in the USA. This footprint will only grow as additive manufacturing (AM) techniques become more pervasive. A pressing concern with AM is that the parts produced often have worse mechanical properties than parts produced from forging or machining. The goal of this collaborative project is to develop new approaches to create a nanoscale physical structure within powder particles in order to improve mechanical properties (strength and thermal conductivity) of final parts. To accomplish this, this research will use lasers to melt different metal and ceramic alloys that have a special chemical composition, known as a eutectic, which produces an internal sheet-like structure. By lasing the powders while they are in a fluid that extracts heat quickly, the eutectic structure can be preserved when the particle solidifies. This work will suspend the powder particles in liquid and solid media that can remove heat, but these media must not react, boil, or obscure the laser. Experiments will be combined with modeling to understand the removal of heat, and to simulate how the internal structure forms within indivdual spherical particles under these conditions. Success in this research would enable a new class of tailored materials to be used in sintering and additive manufacturing to rapidly manufacture complex pieces with improved technical properties. This will have significant direct benefits for the aerospace, automotive, medical products, and defense industries. In addition, the PIs have a good history of recruiting underrepresented minority students in their research, and this effort will continue.Pulsed laser melting and cooling in certain fluids can provide very fast solidification rates to form nanoscale eutectic structures. Unfortunately, in materials with high optical absorption, lasers with nanosecond pulse widths only melt the near-surface region and cannot be considered true bulk processing techniques. This research will circumvent this limitation by using laser irradiation of eutectic alloys in powder form. Most investigations of eutectic solidification in discrete particles have used molten droplets formed by atomization, where heat extraction from the particle into a surrounding gas is inefficient. Although rapid eutectic solidification still occurs, atomization results in highly heterogeneous internal microstructures, which are undesirable with respect to many technical properties. This research will employ particles suspended in liquid or solid media that can extract heat much more efficiently following pulsed laser melting. The suspensions will be volume-restricted such that boiling of the media in contact with the molten particles is suppressed, thereby maintaining effective heat dissipation. In addition, by controlling the laser power and number of pulses, it is possible to partially melt a particle if desired. The experiments will examine these processes in metallic, semiconducting and metal-oxide alloy powders. The dynamic rapid solidification process in bulk and three-dimensional particles will be simulated in detail using the phase field modeling approach. The stability of the nanoscale eutectic structure during spark plasma sintering of the produced particulate material will also be examined.The Broader Impacts of this research include the new processing approaches that create tailored microstructures in feedstock materials for use in sintering and additive manufacturing that will yield improved mechanical and electrical properties in rapidly-manufactured components. This will have significant direct benefits for the aerospace, automotive, medical products, and defense industries.

粉末冶金，其中复杂的零件是通过将金属粉融合在一起的，在美国具有巨大的经济占地面积。随着增材制造（AM）技术变得更加普遍，这种足迹只会增长。对AM的紧迫问题是，所产生的零件通常比锻造或加工产生的零件具有较差的机械性能。这个协作项目的目的是开发新的方法来在粉末颗粒中创建纳米级的物理结构，以提高最终部分的机械性能（强度和热导率）。为此，这项研究将使用激光融化具有特殊化学成分的不同金属和陶瓷合金，称为共晶，产生了内部片状的结构。通过激光粉末在迅速提取热量的流体中激光，当颗粒固化时，可以保留共晶结构。这项工作将悬挂在液体和固体培养基中的粉末颗粒，但这些介质不得反应，沸腾或掩盖激光。实验将与建模相结合以了解热量的去除，并模拟在这些条件下的内部结构如何形成内部结构。这项研究的成功将使一类新的量身定制材料用于烧结和添加剂制造，以快速生产具有改进的技术特性的复杂材料。这将对航空航天，汽车，医疗产品和国防行业具有重大收益。此外，PI在研究中招募了代表性不足的少数族裔学生的良好历史，这项工作将继续进行。某些液体的激光融化和冷却可以提供非常快速的固化速率，以形成纳米级共晶结构。不幸的是，在具有较高光学吸收的材料中，具有纳秒脉冲宽度的激光器仅融化近地表区域，不能被视为真正的散装处理技术。这项研究将通过使用粉末形式的共晶合金激光照射来规避这一限制。离散颗粒中共晶固化的大多数研究都使用了由雾化形成的熔融液滴，其中从粒子中提取热量到周围气体的效率低下。尽管仍然发生快速的共晶固化，但雾化会导致高度异质的内部微观结构，这对于许多技术特性是不可取的。这项研究将采用悬浮在液体或固体培养基中的颗粒，在脉冲激光熔化后可以更有效地提取热量。悬浮液将受到限制性的限制，以便抑制与熔融颗粒接触的介质的沸腾，从而维持有效的热量散热。另外，通过控制激光功率和脉冲数，可以根据需要部分熔化粒子。这些实验将在金属，半导体和金属氧化合金粉末中检查这些过程。将使用相位场建模方法详细模拟整体和三维颗粒中的动态快速固化过程。还将检查纳米级共晶结构的稳定性，在产生的颗粒物材料的火花等离子体烧结过程中。这项研究的更广泛的影响包括新的加工方法，这些方法在原料中创建了量身定制的微观结构，以用于烧结和添加剂制造，以改善可产生的生产。快速制造的组件中的机械和电性能。这将对航空航天，汽车，医疗产品和国防行业具有重大收益。

项目成果

期刊论文数量（3）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Lamellar instabilities during scanning laser melting of Al–Cu eutectic and hypoeutectic thin films

Al-Cu共晶和亚共晶薄膜扫描激光熔化过程中的层状不稳定性

DOI：
10.1016/j.jallcom.2021.158800
发表时间：
2021
期刊：
Journal of Alloys and Compounds
影响因子：
6.2
作者：
Sullivan, E.J.;Tomko, J.A.;Skelton, J.M.;Fitz-Gerald, J.M.;Hopkins, P.E.;Floro, J.A.
通讯作者：
Floro, J.A.

Efficacy of elemental mixing of in situ alloyed Al-33wt%Cu during laser powder bed fusion