It is well–recognized that low Σ-CSL boundaries are highly populated in the grain boundary character distribution (GBCD) for austenitic stainless steel (SS) processed by low strain and subsequent annealing. However, large–strain plus annealing typically tends to introducing numerous random high angle grain boundaries (RHABs) instead of producing high fraction of Σ3, Σ9 and Σ27 boundaries. In this case, the distribution of grain boundary planes of RHABs must be very relevant to the properties of material. The current study is to explore the evolution of GBCD and grain boundary plane distribution (GBPD) in 304 austenitic SS after large strain and subsequent annealing using electron backscatter diffraction (EBSD) and five–parameter analysis (FPA). After solid solution treatment, 304 steel samples were separately processed by multiple forging (MF) and direct rolling (DR) with true strain ε=2 followed by same annealing at 900℃ for 2—120 min. Then the GBCDs and GBPDs of the two groups of samples were examined. The results show that the total Σ3n (n=1, 2, 3) special boundaries in any sample as processed take a length fraction of lower than 45% out of the entire boundaries, and with annealing proceeding the incoherent Σ3 boundaries tend to be tuned into coherent ones and consequently the summation fractions of Σ9 and Σ27 boundaries decrease accordingly. In the two samples which were separately processed by MF and DR but followed by the same annealing at 900℃ for 120 min, their random boundaries or general high angle boundaries (Σ3n special boundaries filtered) mostly appeare to be the <111> twist and <110> tilt boundaries, indicating there exist grain boundary textures (GBT) in both samples. However, in the condition of some misorientations, the GBPDs of random boundaries are quite different in the two samples. For grain boundaries of <111>/30—40? misorientation, more grain boundaries of twist type nearly on the exact {111} plane are found in the specimen processed by DR and annealing for 120 min (DR120) compared to that processed by MF and annealing for 120 min (MF120). For the grain boundaries of <110>/50? misorientation, it was found that most of such boundaries in MF120 are tilt type and positioned on {112}, {113} and {115} planes, whereas those in DR120 are tilt or mixed type positioned on {001}, {111} and {012}. It was suggested that there are distinct effects of pre–processing on the GBPDs of annealed 304 steel.
A molecular dynamics simulation of the rapid solidification process of liquid ZnxAl100−x (x=25, 50, 75) alloys has been performed, and their microstructural evolutions have been analyzed by means of bond–type index method of Honeycutt–Andersen (H–A) and cluster–type index method. Results show that at the cooling rate of 1×1012 K/s all rapid solidified alloys are amorphous structures with majority of 1551 bond–type and icosahedronal basic cluster of (12 0 12 0 0 0).In the rapid solidification process, a peak of the number of 1551 bond–type and icosahedronal basic cluster is demonstrated to exist at the special point corresponding to the glass transition temperature (Tg) of alloys. Tg, the glass forming ability (GFA) and the chemical short–range order (PCSRO) drop with the increase in content of Zn of ZnxAl100−x (x=25, 50, 75) alloys. Segregation and clustering of Zn and Al atoms in molten and rapid solidified alloys are also detected by PCSRO and visualization analysis.