It is an honor to receive the Arthur von Hippel Award, and to become a member of such a select club! It is also a great pleasure to be introduced by my friend Harvey Brooks, who, with his wife Helen, were the first Americans to greet me on my first trip here in 1953.

What has an aging theoretical physicist to do with such a young and budding society as yours? I can only comment on this difficult question by reflecting on the way some of my work has proceeded, and what light this might throw on the development of materials research. I will concentrate on two topics which have been at the core of my work.

I stated research in 1948, under my cousin Charles Crussard, at the Laboratory of Metallurgy of the Paris School of Mines, after a thorough training in mathematics, some training in classical physics and chemistry, and two years of more technical training in mining and metallurgy. I started pulling at test samples and tried to get interested in internal friction. I also learned about x-rays on an old tube set up by my father Edmond Friedel in 1920 at Maurice de Broglie's laboratory, to check the prediction of a layer structure for “smectic” mesophases made by his own father Georges Friedel. I finally used this tube in a very simple piece of experimental work where I measured the angles made at triple nodes by grain boundaries in a sheet of recrystallized aluminum. The idea was to deduce how the grain boundary tension varies with the relative misorientation of the two grains, having checked that the tension does not vary much with the orientation of the boundary with respect to the crystals, a remark that justifies the method.