| 释义 |
subˈcritical, a.
Also sub-critical.
[sub- 14.]
1. Metallurgy. Less than the critical temperature above which ferrite changes into austenite; subcritical annealing, annealing in which the temperature is not raised above this.
1930Trans. Amer. Inst. Mining & Metall. Engineers, Techn. Publ. No. 348. 5 The quenching to this subcritical temperature must be rapid enough to preserve the austenite essentially unchanged. 1935M. A. Grossmann Princ. Heat Treatment viii. 113 Subcritical annealing will not induce as much softness as a full anneal. 1980G. Krauss Princ. Heat Treatment Steel v. 115 Process and recrystallization annealing are similar subcritical annealing treatments usually applied to restore ductility to cold worked steel products.
2. Of a flow of fluid: slower than the speed at which waves travel in the fluid.
1941Civil Engin. Mar. 171/1 The terms ‘tranquil’ and ‘rapid’ have been used..in connection with the Froude criterion... The frequently used terms ‘low-velocity’ and ‘high-velocity’ are..just as inept as the ambiguous ‘subcritical’ and ‘supercritical’. 1943R. C. Binder Fluid Mech. xiv. 215 The hydraulic jump is an abrupt transition between what might be called supercritical and subcritical flow. 1981Sci. Amer. Apr. 138/2 A ridge across a streambed provides an example of how a barrier can create supercritical flow, a standing wave and a hydraulic jump in an initially subcritical flow.
3. Nucl. Physics. Containing or being less than the critical mass (critical a. 7 b).
1945D. Dietz Atomic Energy in Coming Era xii. 146 It was seen..that the mechanism of the bomb would have to bring sub-critical masses of the material together quickly. 1961Engineering 7 Apr. 487/1 Two new light⁓water moderated and natural-uranium fuelled subcritical assemblies are appearing on the nuclear market in this country. 1978Nature 9 Feb. 497/3 Chain reaction is unlikely, since the mass of uranium used in such satellites is normally subcritical. |