"Effect of stoichiometry on the evolution of thermally annealed long-range ordering in Ni-Cr alloys"
David Sprouster, Fei Teng, George Young, Jia-Hong Ke, Julie Tucker,
Ni-based alloys, such as alloys 690 and 625, are widely used in the nuclear industry as structural components, because of their desirable mechanical properties and resistance to stress corrosion cracking. However, in some high chromium alloys, a disorder-order phase transformation near 33 at.% Cr, is known to decrease ductility and fracture toughness. In this study, the ordering transformation is investigated in Ni-Cr binary model alloys to better understand the effects of composition. Model alloys with different stoichiometries (Ni/Cr = 1.8, 2.0, 2.2, 2.4) were isothermally aged up to 10,000 h at three temperatures (373°C, 418°C, and 475°C) and characterized by transmission electron microscopy (TEM), microhardness, and synchrotron-based X-ray diffraction (XRD). TEM results show the evolution of the Ni2Cr (MoPt2-type) ordered precipitates between 3,000 h and 10,000 h with corresponding size of ∼10 nm to 20 nm. Microhardness testing results show that off-stoichiometry (Ni/Cr ≠ 2.0) alloys exhibit a smaller change with ordering compared to the stoichiometric (Ni/Cr = 2.0) alloy at all temperatures. XRD quantifies ordering induced lattice contraction in the matrix structure and the size of the ordered precipitates. No BCC Cr was detected by XRD or TEM during characterization in the range of 29.83 to 35.66 at.% Cr after 10,000 h of aging, confirming that all of the hardening can be attributed to the development of Ni2Cr in alloys ranging from Ni/Cr of 1.8 to Ni/Cr of 2.4.
|"Fuel-cladding chemical interaction of a prototype annular U-10Zr fuel with Fe-12Cr ferritic/martensitic HT-9 cladding" Xiang Liu, Luca Capriotti, Tiankai Yao, Jason Harp, Michael Benson, Yachun Wang, Fei Teng, Lingfeng He, https://www.sciencedirect.com/science/article/pii/S002231152031196X#ack0001 Vol. 544 2021 Link|
|"Measurement of grain boundary strength of Inconel X-750 superalloy using in-situ micro-tensile testing techniques in FIB/SEM system" Yachun Wang, Xiang Liu, Daniel Murray, Fei Teng, Wen Jiang, Mukesh Bachhav, Laura Hawkins, Emmanuel Perez, Cheng Sun, Xianming Bai, Jie Lian, Colin Judge, John Jackson, Robert Carter, Lingfeng He, Materials Science & Engineering Vol. 849 2022|
|"Effect of Thermal And Irradiation-induced Long Range Ordering in Ni-Cr Model Alloys" Fei Teng, David Sprouster, Peter Hosemann, Li-Jen Yu, Emmanuelle Marquis, Julie Tucker, NuMat October 14-18, (2018)|
|"Irradiation-accelerated phase transformations for low-temperature phase diagram development" Julie Tucker, Fei Teng, Emmanuelle Marquis, David Sprouster, MRS November 25-30, (2018)|
|"Role of aging and irradiation on ordering phase transformations in Ni-Cr alloys" Julie Tucker, Fei Teng, Emmanuelle Marquis, MRS Spring Meeting April 16-20, (2018)|
|"The Role of Ordering Phase Transformations in Micro-mechanics of Ni-Cr Alloys for Nuclear Applications" Fei Teng, Stephanie Pitts, Hi Vo, Peter Hosemann, Julie Tucker, TMS March 11-14, (2018)|
|DOE Awards 37 RTE Proposals - Awarded projects total nearly $1.4M in access awards Tuesday, July 14, 2020 - News Release, Calls and Awards|