Discussion of Six Papers From May 2013 Issue

Abstract

The May 2013 issue of Metallurgical and Materials Transactions A is a typical issue, containing a number of papers, all of which would be explicable assuming the near-universality of the presence of oxide bifilms in metals as a result of the entrainment of the surface oxide film during pouring. The unbonded interface between the necessarily doubled-over surface film, often only a few nanometers thick, and often occurring at grain boundaries, appears to be the cause of grain boundary failures and the initiation of cracks. The precipitation of second phases on the outer surfaces of the bifilm, in good atomic contact with the matrix, explains the apparent brittleness of many intermetallics and second phases. The number of papers from the May issue of MMTA illustrates the ubiquitous presence of bifilms, up to now almost unknown, and their central importance in physical metallurgy, and their possible control, in turn, by up-to-date process metallurgy.