Department of Materials Science and Engineering, Texas A&M University, College Station, TX 77843, USA.
Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843, USA.
Ultramicroscopy. 2023 May;247:113700. doi: 10.1016/j.ultramic.2023.113700. Epub 2023 Feb 10.
In this work, we developed a method using precession electron diffraction data to map the residual elastic strain at the nano-scale. The diffraction pattern of each pixel was first collected and denoised. Template matching was then applied using the center spot as the mask to identify the positions of the diffraction disks. Statistics of distances between the selected diffracted disks enable the user to make an informed decision on the reference and to generate strain maps. Strain mapping on an unstrained single crystal sapphire shows the standard deviation of strain measurement is 0.5%. With this method, we were able to successfully measure and map the residual elastic strain in VO on sapphire and martensite in a NiTiHf shape memory alloy. This approach does not require the user to select a "strain-free area" as a reference and can work on datasets even with the crystals oriented away from zone axes. This method is expected to provide a robust and more accessible alternative means of studying the residual strain of various material systems that complements the existing algorithms for strain mapping.
在这项工作中，我们开发了一种使用进动电子衍射数据来绘制纳米级残余弹性应变的方法。首先收集每个像素的衍射图案并对其进行去噪。然后使用中心斑点作为掩模应用模板匹配来识别衍射盘的位置。选择的衍射盘之间距离的统计信息使用户能够在参考选择上做出明智的决定，并生成应变图。在未受应变的蓝宝石单晶上进行应变映射表明应变测量的标准偏差为 0.5%。使用这种方法，我们成功地测量并绘制了蓝宝石上 VO 和 NiTiHf 形状记忆合金中马氏体的残余弹性应变。这种方法不需要用户选择“无应变区”作为参考，并且即使晶体偏离晶带轴，也可以在数据集上工作。该方法有望为研究各种材料系统的残余应变提供一种稳健且更易于使用的替代方法，补充了现有的应变映射算法。
