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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Vacuum thermionic work function for well-outgassed polycrystalline surfaces, noting techniques for accurate measurement of current, area and temperature values
Phase equilibrium of titanium aluminum molybdenum system in titanium rich alloy field
Phase transformations in titanium aluminum molybdenum alloys
Phase diagram of titanium vanadium niobium molybdenum system
Molecular orbital techniques used to find cubic field splitting 3a of certain ions in periodic group II-VI compounds of T sub d symmetry
Welding parameters and elevated temperature aging and strength characteristics of transition joints between chromium molybdenum alloy steel and stainless steel
Mechanical properties of chromium molybdenum steel
Vacuum thermionic work function and thermal stability measurements on crystal surfaces, discussing results on carbides, diborides and disilicades
Molecular orbital method based on atomic self consistent field functions and applicable where pi electron restrictions not fulfilled
Surface electron and ion emission from refractory metal compounds in cesium vapor, showing electron emission S curves and surface ionization critical temperature envelopes
Titanium alloys hot salt stress corrosion cracking, studying effects of chlorides and surface oxides
Nickel base alloy with resistance to oxidation at high temperatures and superior stress-rupture properties
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The empirical pseudopotential method (EPM) is used to calculate the band structure of tungsten and molybdenum. Agreement between the calculated reflectivity, density of states, density of states at the Fermi surface and location of the Fermi surface from this study and experimental measurements and previous calculations is good. Also the charge distribution shows the proper topological distribution of charge for a bcc crystal.
Cooled target collection techniques were used to study the formation of volatile products when samples of Cr, Ti, IN-738, 713C, NASA-TRW VIA and B-1900 were exposed, at elevated temperatures, to oxidizing environments containing H2O(g) and NaCl(g). Samples were heated to 1050 C in one atmosphere of slowly flowing oxygen, saturated with water at 21 C, and containing about 50 ppm NaCl(g). Volatile products were detected for all materials except B-1900 and Ti. High pressure mass spectrometric sampling was used to directly identify volatile products emanating from samples of Cr and IN-738 subject to the above environments.
Creep-fatigue tests were conducted on annealed 2.25Cr-1Mo steel in air at 538 C involving interspersion of rapid strain cycles (0 to 22 cycles) between constant tensile stress-hold periods (23 or 47 hours). Life predictions were made on the basis of the strain range-life relations obtained from short-time material characterization tests on tubular specimens taken from the same heat as the specimens for the creep-fatigue tests. The creep-fatigue tests lasted from about 500 to 5000 hours, while the short-time tests used as the prediction basis lasted from 0.1 to 100 hours. By partitioning the creep and plastic strains within every cycle and summing the damage on a cycle-by-cycle basis, the predicted lives agreed with the observed ones within factors of two.
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Experience in plane-strain fracture toughness testing per ASTM Method E 399 is considered along with fracture toughness testing using the C-shaped specimen, an analysis of radially cracked ring segments subject to forces and couples, compliance calibration of specimens used in the R-curve practice, heavy-section fracture toughness screening specimen, and sharply notched cylindrical tension specimens for screening plane-strain fracture toughness. Attention is also given to an investigation of some problems in developing standards for precracked Charpy specimen strength ratios, fracture testing with surface crack specimens, and the estimation of plane strain fracture toughness values from slow bend precracked Charpy specimen strength ratios.