ENGINEERING DEPARTMENT SHOWS FILM ON METALS

The first showing at Harvard of the Metallurgy Department's film "Some Surface Changes in Metals at High Temperatures" occurred recently in the Engineering School, Pierce Hall, before the New England Group of the Harvard Engineering Society. The film was produced last summer in the Metallurgical Laboratories in Pierce Hall by B. A. Rogers, graduate student in physics and metallurgy and Dr. L. R. van Wert, of the School's Metallurgical staff. Next month, showings will be given in Pacific Coast cities, and later, perhaps, in Germany and Italy whence requests for showings have come.

First Successful Attempt

It is believed that the film represents the first successful attempt to record on any movie film those surface changes in metals which directly result from profound internal changes taking place in the metal at certain temperatures. The temperatures concerned are often very high, and the surface changes themselves are too small to be visible except under magnification.

The film shows among other things two phenomena produced on heating pure iron. The first of these is the development of grain boundaries. Iron, like all metals, is a crystalline complex, and is made up of a great number of individual crystals. The boundaries between the several crystalline units may be revealed under proper preparation of the sample as a "network." At the start of the heating of the iron sample in this study, no boundaries were in evidence, but as the temperature slowly increased they became gradually visible. This was due to the "etching effect" of the hydrogen used to prevent oxidation of the sample.