التفاصيل البيبلوغرافية
| العنوان: |
Thermal stabilizing and toughening of a dual-phase Nb alloy by tuning stabilizing element C in Nb-BCC. |
| المؤلفون: |
Zhang, Yafang, Zhao, Xiaojun, Liu, Sainan, Li, Wei, Zhou, Kechao, Xiao, Lairong, Song, Miao, Cai, Zhenyang |
| المصدر: |
Journal of Materials Science & Technology; Jul2024, Vol. 186, p207-218, 12p |
| مصطلحات موضوعية: |
DUAL-phase steel, NIOBIUM alloys, TENSILE strength, THERMAL stability, ALLOYS, THERMAL properties, THERMOCYCLING, TORSIONAL load |
| مستخلص: |
• Thermal stabilizing and toughening of a dual-phase Nb alloy are achieved by tuning stabilizing element C in Nb-BCC. • The 3.1 % lattice expansion resulting from the BCC-to-FCC transformation compensates for the lattice relaxation induced by the precipitation of interstitial C atoms from the BCC matrix. • The exceptional performances can be attributed to the network skeletal structure of discontinuous carbide GBs and the presence of BCC+FCC dual-phase grains (K-S relationship). • The discontinuous carbide GBs can impede grain growth, block and transfer dislocations, and mediate localized deformation. Niobium alloys have found extensive application in industries, such as aerospace, nuclear reactor, and emerging electronic technologies, owing to their high melting point, low density, and remarkable formability. Nevertheless, they still fall short in terms of comprehensive strength, toughness, and thermal stability when subjected to complex impacts and/or torsional forces during service. Here, a dual-phase (BCC/FCC) Nb alloy with attractive mechanical properties and thermal stability was designed by tuning stable element C in the Nb-BCC matrix assisted by hot deformation and aging processes. Our findings reveal that the formation of discontinuous carbides at the grain boundary promotes the phase transformation of the matrix from BCC to FCC (K-S orientation relationship), resulting in the formation of FCC thin layers and nano particles. This unique configuration hinders the slipping of dislocations during deformation and impedes the degeneration of microstructures during the thermal cycling process from 200 °C to 900 °C. Moreover, the discontinuous carbides at GBs provide channels to transfer dislocations between various phases and/or grains, which results in attractive mechanical properties and thermal stability. The ultimate tensile strength, yield strength, elongation, and elasticity modulus of the designed Nb alloy reach impressive values of 790.5 MPa, 436.5 MPa, 39.1 %, and 63.5 MPa, respectively. These observations provide guidelines for designing dual-phase Nb alloys with remarkable strength, toughness, and thermal stability for aerospace applications by tuning the stabilizing element C in the Nb-BCC matrix. [Display omitted] [ABSTRACT FROM AUTHOR] |
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