In situ observation of crystal rotation in Ni-based superalloy during additive manufacturing process

Abstract

Understanding the dynamic process of epitaxial microstructure forming in laser additive manufacturing is very important for achieving products with a single crystalline texture. Here, we perform in situ, real-time synchrotron Laue diffraction experiments to capture the microstructural evolution of nickel-based single-crystal superalloys during the rapid laser remelting process. In situ synchrotron radiation Laue diffraction characterises the crystal rotation behaviour and stray grain formation process. With a complementary thermomechanical coupled finite element simulation and molecular dynamics simulation, we identify that the crystal rotation is governed by the localised heating/cooling heterogeneity-induced deformation gradient and recognise that the sub-grain rotation caused by rapid dislocation movement could be the origin of granular stray grains at the bottom of the melt pool.

The Microstructure, Solidification Path, and Microhardness of As-Cast Ni-Al-Cr-Os Alloys in a Ni-Rich Region

“…Nickel-based single-crystal superalloys are widely applied as high-temperature-resistant materials in the aerospace domain on account of their superior mechanical properties [1][2][3][4]. In order to fulfill the increasing requirements for better performance under extreme conditions, the manufacturing of novel nickel-based single-crystal superalloys with properties suitable for high-temperature, mechanical, and creep resistance needs to be investigated, e.g., by adding different alloying elements [5][6][7].…”

激光增材制造金属功能材料及其原位同步辐射研究（特邀）

“…(a)-(c) Variations in the DSC curves when the scanning speed, scanning spacing, and laser power are changed; (d) linear relationship between each parameter and the peak temperature of martensitic transformation 7 Effect of remelting process on the properties of additively manufactured metal functional materials. (a)-(b) Effect of remelting of SLM Cu -Al -Ni -Mn alloy interlayers on the microstructure and austenite phase transformation peak temperature [90] ; (c) principle of laser insitu heat treatment in L -DED [91] ; (d) NiTi alloy with insitu laser heat treatment behaves larger enthalpy of phase transition [91] 1002305 -8 11 Insitu synchrotron XRD was used to characterize the stressinduced martensitic phase transformation of NiTi SMAs [66] MicroXAS/ MS beamline X-ray energy 24 keV [40][41] /61.3 keV [49][50] 79 keV [48] , 98.02 keV [55,108] , 103.43 keV [54] 20 keV [42][43] 68.4 keV [47] 9.3 keV [45] , 12 keV [44] , 17.2 keV [49] 1002305 -11 [52][53] 70 keV [51] Highenergy white/ monochromatic light [112] 特邀综述…”

“…光 重 熔 过 程 中 具 有 代 表 性 的 Laue 衍 射 图 的 时 间 序 列 ［112］ 。 (a)~(e)在 0、 225、 250、 350、 1000 ms 时 采 集 的 Laue 衍 射 图 像 ； (f)0 ms 和 1000 ms 时 γ ( 晶格平面衍射斑的局部放大图； (g)~(h) γ (113)晶格平面在 χ 方向(g)和 2θ 方向(h) 上随时间的变化图。激光器在 150 ms 开启， 在 250 ms 关闭 Fig. 16 Time series of the representative Laue diffraction patterns during laser remelting processes[112] . (a) -(e) Laue diffraction images collected at 0, 225, 250 , 350, and 1000 ms; (f) Local enlarged drawings of the diffraction spots of γ( planes at 0 and 1000 ms; (g)-(h) variation diagrams of γ(113) crystal plane with time in the χ direction (g) and 2θ direction (h).…”