Grain Boundary Segregation in Al-Zn-Mg Alloys --Implications to Stress Corrosion Cracking.

摘要

Prior studies on grain boundary segregation in Al-Zn-Mg have shown that free Mg is present along the grain boundaries in these alloys under all heat-treat conditions. In this paper, further studies on grain boundary segregation in Al-Zn-Mg alloys are outlined. A physical basis for the observed segregation profiles is provided through the vacancy pump model developed by Anthony. The implications of the observed segregation to stress corrosion cracking (SCC) and other environmentally-induced embrittling phenomena (where hydrogen could possibly play a dominant role) are discussed in terms of a possible Mg-H complex formation. A wide body of circumstantial evidence from several areas for such an interaction is provided. The dependence of this segregation on boundary type is explored and texture control is proposed as a possible means of controlling segregation and enhancing resistance to stress corrosion cracking. (Author)