EDITOR'S COLUMN
from the same material were ini tially selected. Of these two samples, which are identical except tor size, the smaller (No. 461) was chosen because it had received more severe cold-working than the larger, and hence exhibited a finer grain size. The NBS electron probe microanalyzer was used to determine the homogeneity of both nickel and iron at the 2- to 4-micron level of spatial resolution in the longitudinal, trans verse, and normal directions. In clusions in the samples were identi fied, their volume percentage cal culated, the mean free path between them determined, and their number and size distributions found by us ing both electron probe and chemi cal etching techniques. Concerning the steel itself, the following information was ob tained: (a) the ferrite and pearlite percentages in the worked structure of the steel, (b) the mean free path for ferrite and pearkte, and (c) the grain size of the steel. To obtain this information, a technique of quantitative metallography em ploying a digital computer capable of accepting suitable photomicro graphs and of directly printing out the desired information was used. With this method, high-contrast black and white photomicrographs of the specimen are scanned and the resulting data introduced into the computer in binary machine code. Twenty-eight general computer op erations can be performed on each photomicrograph by feeding master routine into a portion of the computer memory. These analyses resulted in a more complete char acterization of No. 461 than had previously been available. Work is in progress at the Bureau to determine the feasibility of using other NBS spectrochemical stand ards for mieroanalytical techniques. Standards available from NBS are listed in Standard Materials, Miscellaneous Publication 241, which may be obtained for 30 cents from the Superintendent of Docu ments. Washington, D. C. 20402.
NEW QUADRUPOLE MASS SPECTROMETER ...high performance in low cost modules
Details on AMP-3 Mass Filter available by sending for Data File A 401-64.
Basic unit, residual gas analyzer has nude ion source for location inside space chamber for maximum sensitivity. Quadrupole tube is bakeabie to 450°C. No magnets required, Smallest detectable partial pressure is below 10 -12 Torr. Optional electron multiplier achieves 10_spectra/sec. max. scan rate for chromatograph studies and rapidly changing molecular beam analysis. • Modular construc tion allows adding oscilloscope and recorder, bakeout system, ion or air-cooled diffusion pumping unit with choice of gas inlet systems. • For complete information, write for catalog which also contains data on eight other M A T analytical instruments, including dc ampli fier, Betograph and Tastpolarograph.
gas
spectrum
shows portion
Residual
of 1-120
amu linear
mass
range
and M ; Δ Μ of ISO.
bold and serviced in U. S. and Canada by APPLIED PHYSICS CORPORATION 2724
SOUTH PECK ROAD • MONROVIA, CALIFORNIA
INSTRUMENTS
Circle Να. 199 on Readers' Service Card-
Raman/ UV ; IFt Recording Spectrophotometers
· Vibrating Reed
Electrometers
