Industrial Research 



297 



did not develop rapidly, though some was used in 

 Zeppelins during the World War. About 20 years ago, 

 Merica and coworkers at the National Bureau of 

 Standards discovered and clearly set forth the principles 

 involved, putting the precipitation hardening by heat 

 treatment on a rational basis. It was then possible to 

 concoct other alloys that fitted in with the principles 

 in the hope of securing analogous strengthening by 

 analogous heat treatment, and to subject known alloys 

 to suitable treatment in the hope of improving their 

 properties. Today hundreds of useful alloys with a 

 desirable combination of formerly unattainable proper- 

 ties are in commercial service. Beside a variety of 

 aluminum alloys there are many copper-base alloys, 

 including beryllium copper; steels, such as copper 

 steels; lead-base alloys, nickel-base alloys, and special 

 iron-tungsten and iron-molybdenum alloys the useful 

 properties of which depend on the application of these 

 principles. Improved methods of heat treating high- 

 speed steels are based on them also. The principles 

 likewise explain some harmful changes in low-carbon 

 steels and in various alloys at high temperature and 

 make it possible to avoid them to some degree. 



Merica's work was one of the outstanding examples 

 of the value of getting at fundamentals and of steering 

 thinking into new channels. Getting our thinking out 

 of ruts, often by borrowing ideas and methods from 

 other fields, is not the least important byproduct of 

 research. Another example of this may be cited. 



Powder Metallurgy 



Analogous to the practice common in the ceramic and 

 plastics industries, of making products by agglomeration 

 rather than by melting, the idea of pressing and sinter- 

 ing metal powder into coherent porous products, which 

 may or may not then be worked into less porous form, 

 has already been utilized in making ductile tungsten 

 and the tungsten carbide tools. "Powder metallurgy" 

 for the manufacture of porous, oil-retaining bearings, 

 and as an alternative to forming by casting, or forging, 

 or machining from solid stock, is on the horizon as a 

 possibly important new branch of metallurgy, applicable 

 also to the production of alloy combinations that cannot 

 readily be made by older methods. In specific in- 

 stances the method is well established; its widespread 

 application is now more a matter of economics than of 

 technology. 



Adaptations From Other Sciences — 

 Electron Diffraction 



The application of the skills of other sciences to 

 metallurgy is indispensable. Within the last decade 

 the physicist has developed a new tool, electron diffrac- 

 tion, which showed promise of giving information about 

 conditions at the surface of metals, the mechanism of 



the progress of corrosion, etc., that it was impossible to 

 procure by previously existing methods. Metallurgical 

 research workers soon took up the new tool and devel- 

 oped the necessary special technique, with great ad- 

 vantage to metallurgical science. Entirely invisible 

 films only about a fifth of a millionth of an inch tliick 

 deposited upon the surface of metals have not only 

 been shown by electron diffraction to be present there, 

 but the composition and structure of the films have 

 been established by the same means.'" 



Mineralogical Methods Utilized 



The mineralogist has accumulated information on the 

 composition and means of recognizing naturally occur- 

 ring minerals, and together with the physical chemist, 

 has developed methods of charting and recognizing what 

 might be termed artificial minerals. He has used the 

 petrographic microscope in his work, much as the metal- 

 lurgist uses the metallurgical microscope. Those metal- 

 lurgists engaged in the smelting of ores find it necessary 

 to purify, or "beneficiate" the ores by mechanical sep- 

 aration of their wanted from their unwanted constit- 

 uents. One method of separation is the flotation 

 process previously mentioned in connection with molyb- 

 demmi and copper. To make these separation processes 

 applicable, the ore must be groimd so that the particles 

 of the desirable and the undesirable constituents are 

 separated. If, however, the constituents are in such 

 intimate mineralogical combination that separation by 

 grinding is impossible, mechanical separation processes 

 are inapplicable and chemical methods must be sought. 



Application of mineralogical knowledge and technique 

 allows the metallurgist to start at once upon the proper 

 road of investigation. Mineralogical technique, includ- 

 ing the use of polarized light, also serves the metallurgist 

 in the study of nonmetaUic impmities occurring as 

 inclusions and thereby enables him to detect the source 

 of the impurities and take steps toward eliminating 

 them. 



The physicist has developed the use of polarized light 

 for studying stress distribution in transparent models. 

 This is a matter of applied mechanics rather than 

 metallm-gy, but it greatly helps the metallurgist in that 

 it proves that the designer can do much to mitigate 

 stress concentration by proper attention to geometric 

 form and is thereby enabled to reduce his demands 

 for materials capable of resisting such high stress 

 concentrations. 



Instruments and Equipment 



Modern metallurgical research requires equipment 

 and instruments for precise quantitative measurements 

 to an ever increasing degree. A great change in flying 



" Nelson, H. R. The low temperature oiidation of iron. Journal of Ckemical 

 Physics, 6. 606-n (1938). 



