查看更多>>摘要：A new Ni+Zr co-alloyed FeCrAl-ODS(oxide-dispersion-strengthened)ferritic alloy was fabricated by ball-milling and hot-isostatic-pressing.Using electron microscopy and atom probe tomography,the dispersive formation of high density core-shelled nano-particles of various sizes was confirmed with a common B2-NiAl shell.Among which,median-sized nano-particles(20-50 nm)typically have an Y4Al2O9 nano-core of＜～20 nm,ultra-fine nano-particles(＜～20)nm have an Y4Zr3O12 nano-core of＜～10 nm,and larger-sized nano-particles(50-100 nm)incorporate an ultra-fine Y4Al2O9 nano-core and a few ultra-fine Y4Zr3O12 nano-oxides.All these nano-phases were highly coherent with the ferritic matrix.No large Y-Al-O nano-oxides were formed.The total number density of ultra-fine nano-particles was estimated as～2× 1023 m-3 with a mean size of 6.3 nm only,and accordingly,the new alloy achieved an excellent combination of strength and ductility at high temperatures.
查看更多>>摘要：The objective of this study was to investigate the influence of strengthening mechanisms on the high-temperature mechanical properties of China low-activation ferrite(CLF-1)steel,which underwent thermodynamic design and thermo-mechanical treatment(TMT).The microstructure characterization in the normalized and tempered condition and the TMT condition was carried out using optical microscopy,X-ray diffractometer,and scanning electron microscopy with electron backscatter diffraction.High-resolution transmission electron microscopy was employed to determine the crystallographic structures of precipitated phases.The results indicated that the addition of Ti led to an increase in the allocation of C in MC phase and an enhancement in the content of MC phase.Compared to CLF-P steel in the normalized and tempered condition,a 1.5-fold increase in dislocation density and an order of magnitude improvement in MX phase density were achieved after TMT.The formation of high-density nano-scale MC phases during TMT played a significant role in precipitation strengthening due to their favorable coherent relationship with the matrix and low interfacial free energy.The excellent high-temperature mechanical properties observed in CLF-P steel after TMT can be attributed to the combined effects of precipitation strength-ening,dislocation strengthening,and lath strengthening.
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维普