An Ke, Armitage Douglas P, Yu Zhenzhen, Dickson Richard W, Mills Rebecca A, Feng Zhili, Skorpenske Harley D
Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Rev Sci Instrum. 2018 Sep;89(9):092901. doi: 10.1063/1.5033566.
neutron scattering is a powerful tool to reveal materials atomic structural response such as phase transformation, lattice straining, and texture under external stimuli. The advent of a high flux neutron source such as the Spallation Neutron Source (SNS) allows fast measurement in even non-equilibrium conditions, i.e., phase transformation in steels. However, the commercial fast heating apparatus such as commercial physical simulation equipment is not designed for neutron scattering, which limits its application to materials research by using neutrons. Here we present a resistive heating gas enclosure loadframe (RHEGAL) for non-equilibrium phase transformation studies by using neutron scattering, which takes the advantage of high flux neutron sources like SNS. RHEGAL enables fast resistive heating of metal samples to 1200 °C at a rate up to 60 °C/s in an inert atmosphere. It provides both horizontal and vertical positions for scattering optimization. The mechanical loading capability also allows high temperature tension above the oxidation temperature limit. The optimized translucent neutron scattering window by silicon allows both reflection and transmission measurements, making this equipment applicable for neutron diffraction, small angle scattering, and imaging. To demonstrate the fast heating capability, the phase transformations of an example of advanced high strength steel heated at 3 °C/s and 30 °C/s were measured with the VULCAN engineering diffractometer, and the different phase transformation kinetics by neutron diffraction were presented.
中子散射是揭示材料原子结构响应的有力工具，比如在外部刺激下的相变、晶格应变和织构。像散裂中子源（SNS）这样的高通量中子源的出现，使得即使在非平衡条件下也能进行快速测量，例如钢中的相变。然而，诸如商业物理模拟设备等商业快速加热装置并非为中子散射而设计，这限制了其在材料中子研究中的应用。在此，我们展示了一种用于通过中子散射进行非平衡相变研究的电阻加热气体密封加载框架（RHEGAL），它利用了像SNS这样的高通量中子源的优势。RHEGAL能够在惰性气氛中将金属样品以高达60℃/s的速率快速电阻加热至1200℃。它提供水平和垂直位置以优化散射。其机械加载能力还允许在高于氧化温度极限的情况下进行高温拉伸。通过硅优化的半透明中子散射窗口允许进行反射和透射测量，使得该设备适用于中子衍射、小角散射和成像。为了展示快速加热能力，使用VULCAN工程衍射仪测量了以3℃/s和30℃/s加热的先进高强度钢示例的相变，并给出了通过中子衍射得到的不同相变动力学。
