This is the fifth and final article in the series on the activities of Graduate School of Engineering, by Howard Aiken, Instructor in Physics and Communication Engineering.
The progress of our industrialized civilization depends not only on the ingenuity of our engineers in the conception of new methods for supplying our material needs, but also on their ability to carry out ideas in actual practice. This necessitates the use of a variety of materials for the construction of tools, machinery, and other products. Among these, metals and metallic alloys stand preeminent. Industrial builders in all fields are constantly demanding metals which will successfully meet more severe and exacting needs. Unless the metallurgist is able to supply this need further advance must of necessity come to a halt. The remarkable progress in the art of metallurgy during the last thirty years has been accomplished by the rigorous application of scientific methods leading to the development of the science of metallography.
Efficient Material Produced
Already this youthful science has given to the world products which a score of years ago would have been considered as belonging only to the field of the dreamer; steel which neither rusts nor corrodes; steel which does not scale at elevated temperatures; case-hardened articles possessing superhardness without introduction of additional carbon; metallic carbides harder than sapphire; light alloys possessing great strength and ductility and resistance to corrosion, making progress in aircraft possible; and magnetic alloys having unusual properties, making possible further development in electrical engineering.
McKay Founder of Science
The department of metallurgy of the Graduate School of Engineering has been associated with the development of Metallography from its beginning. Dr. Albert Sauveur, Gordon McKay Professor of Metallurgy, Emeritus, founded the science in America, and is now the dean of American Metallurgists. His treatise on "The Metallography and Heat Treatment of Iron and Steel" is the standard work of reference in its field.
Since the retirement of Dr. Sauveur, the department of metallurgy has been under the leadership of Dr. A. B. Greninger and Dr. R. R. Hultgren who offer courses in the fundamentals of metallurgy to students in the College, and advanced courses in metallography and the physics of metals to graduate students working for the higher degrees in engineering.
Studies Structure of Metals
The department concerns itself largely with the theory of metals and alloys based on the study of the crystalline structure through application of X-ray diffraction technique and microscopy. Recently Dr. Hultgren has developed a cathode ray oscillograph apparatus for the measurement of the position of X-ray diffraction lines recorded on photographic film. This apparatus permits the position of the diffraction lines to be measured with great accuracy and rapidity, and is proving a valuable tool in the determination of the distances between the atoms in metallic crystals. These distances are of the order of the hundred millionth part of a centimeter and may be measured with an accuracy of one part in ten thousand.
Electric Bombardment Furnace
Dr. Hultgren has also developed an electron bombardment furnace in which small samples of metallic alloys are heated by the impact of electrons at high velocity. This electron bombardment furnace is capable of heating several grams of metal to a temperature of 3000 degrees Centigrade, and its limiting high temperature is set by the lack of suitable high melting crucibles to contain the sample under study rather than by any inherent limitation in the apparatus itself. This furnace makes possible the experimental investigation of many alloys which were formerly very difficult to melt under the controlled conditions necessary for scientific research.
Dr. Greninger is at present studying Martensite, one of the hardening constituents of steel. Although a great deal of work has been done on this problem, very few fundamental facts are as yet known. However, Dr. Greninger is attacking the problem with great success, as the first step in a new extended study of the transformations which occur during the heat treatment of steel.
Measures Crystal Spacings
Dr. Greninger has also developed a method of utilizing X-ray diffraction comeras for the measurement of crystal spacings. Through the use of this camera one photograph taken in less than an hour and interpreted in a few minutes will completely establish the orientation of metallic crystals, whereas formerly a careful observer might spend the larger part of a day in getting the same results. This method has now been adopted as standard practice in most metallurgical laboratories throughout the country. Dr. Greninger is also engaged in the study of the change of crystal structure in the send state.
The laboratory of the department of metallurgy, housed in the Rotch Building, has been completely rebuilt during the last two years and includes the best facilities obtainable for its purposes both in instruction and research. For instance, the laboratory possesses one of the best and most recently developed metallographic microscopes. The X-ray apparatus is of the latest design and the facilities for the preparation and heat treatment of alloy samples are unusually good.
At the present time metallography as a science offers an unusually good field for advanced study. The science is still young and many important and fundamental discoveries are yet to be made. There is a constant and growing demand for well-trained metallurgists in the various industrial research laboratories throughout the country. In order best to meet the requirements of these laboratories the Department of Metallurgy is concentrating all its efforts on the development of the fundamental theory of the subject rather than miscellaneous detailed applications to specific industrial processes.