2005 Volume 69 Issue 12 Pages 1089-1098
The present work aims to clarify the atomic arrangements at the austenite/martensite interfaces for the nucleating martensite and the edge of growing martensite. The Fe-23Ni-3.8Mn alloy and the Fe-9Cr-1.1C alloy with the K-S orientational relationship with the {112} habit plane were observed with the high resolution electron microscopy. At the very tip of wedge-shaped growing martensite, dislocations queues up on every about six (111)f layers along the interface, with their extra-half plane in the austenite. The nucleus of the martensite was observed in the Fe-9Cr-1.1C alloy. The nucleus has the K-S orientational relationship with a habit plane of (111)f(//(011)b) and an wing-like shape, and remarkably expands in the direction of [101]f(//[111]b). The crystal structure of the nucleus shows a lattice transition region from fcc to bct toward inside, and the transformation into the final martensite structure (bct) is still incomplete even at the center of the nucleus.
