Format:
1 Online-Ressource (26 p)
Content:
In the work, high nitrogen γ-Fe alloy iron was fabricated by N 2 pressure sintering in which the N content could be up to 0.521wt%. Microstructure and mechanical properties were systematically studied. The increased activity of N with added N 2 pressure accelerated the generation of MnSiN 2 with an orthorhombic structure which had a orientation relation of ( [[EQUATION]] ) γ-Fe // ( [[EQUATION]] ) MnSiN2 with γ-Fe, and the HRTEM map displayed the incoherent interface of duplex phase on account of a large difference of the crystal plane distance between ( [[EQUATION]] ) γ-Fe (d (1-11) =0.2082nm) and ( [[EQUATION]] ) MnSiN2 (d (12-1) =0.2428nm). Also, the ordered structure formed, with a superlattice structure of selective electron diffraction spots, due to the solution atoms such as Mn or N atoms in γ-Fe. Also, the elevated nanohardness for austenite grains implied the solution strengthening mechanism of N. The austenite grain size decreased gradually according to EBSD maps, corresponding to 9.81, 7.27 and 6.22um, indicating that the formation and precipitation of MnSiN 2 hindered the grain growth and led to the finer grain structure with the increased pressure of 0.05Mpa, 0.5Mpa and 1Mpa. The solution strengthening combined with crystal strengthening was the main reinforcement mechanism rather than precipitation strengthening, which enhanced the hardness and wear resistance
Language:
English
