A/D Type Twin Boundary in 18R Martensite in a Cu-Zn-Al Alloy

摘要

The A/D type twin boudnary between 18R martensite paltes in Cu-Zn-Al alloy has been stuide dby transmission electron microscope(TEM) and high resolution electron microscoep (HREM). It is curved in TEM and has irregularly-serrated steps in HREM. The boudnary segments consist of respective basal planes of the two variants. The randomly distributed faults have not obvious influence on the boundary orientation. The inferred boundary energy indicates that the deviation from exact twon orientation and a preferential orientation for lower boundary energy result in the irregularly-serrated steps.