GOALI: Nanoparticle Metrics for Computational Materials Mechanics

用于计算材料力学的纳米颗粒度量学这个GALI计划的科学目标是直接评估测量和计算的亚微米长度尺度。此外，它的工程目标是将其应用于保护和制造磁记录系统的改进材料工艺。科学上，我们正在利用纳米压痕、原子力显微镜和透射电子显微镜测量20到200 nm范围内无缺陷纳米球的机械响应。在最小尺度上使用修正的嵌入原子间相互作用势结合较大尺度上的离散化位错动力学来评估具有相同边界条件的相同数目的原子的直接评估。用于评估与梯度塑性、体积与表面积比和过剩表面应力相关的长度尺度的参数包括位错成像、应变硬化措施和表面修饰。关于工程目标，将寻求改进的材料工艺，利用原子层沉积(ALD)表面修饰的纳米球实现薄膜的平坦化。这种与目前正在研究的用于磁记录的磁头的纳米级保护相同的ALD工艺将被应用于磁头介质，其目标是提高对抗局部摩擦和磨损的性能。明尼苏达大学首席研究员W.W.Gerberich联合首席研究员C.B.卡特，明尼苏达大学W.A.柯廷和A.NeedlemanBrown大学

Nanoparticle Metrics for Computation Materials MechanicsABSTRACT This GOALI program has the scientific goal of directly evaluating measured and computational submicron length scales. Additionally, it has the engineering goal of applying this to improved materials processes for protecting and manufacturing magnetic recording systems. Scientifically, we are measuring the mechanical response of defect-free nanospheres in the 20 to 200 nm range utilizing nanoindentation, atomic force microscopy, and transmission electron microscopy. Direct evaluation of the identical number of atoms with the identical boundary conditions are being evaluated using modified embedded atom interatomic potentials at the smallest scales coupled with discretized dislocation dynamics at the larger scale. Parameters to evaluate length scales associated with gradient plasticity, volume to surface ratios, and excess surface stress included dislocation imaging, strain hardening measures, and surface modification. Regarding the engineering goals, improved materials processes for planarization of thin films utilizing nanospheres surface-modified by atomic layer deposition (ALD) will be sought. This same ALD process, as currently being investigated for nanometer level protection of heads for magnetic recording will be applied to head media with algorithms for improved performance against localized friction and wear as a goal.Principal InvestigatorW.W. Gerberich, University of MinnesotaCo-Principal InvestigatorsC.B. Carter, University of MinnesotaW.A. Curtin and A. NeedlemanBrown University, Provi