| 释义 |
eutectoid, a. and n. Metallurgy.|juːˈtɛktɔɪd|
[f. eutectic a. and n. + -oid.]
A. adj. That is a eutectoid; of or pertaining to a eutectoid or its transformation; eutectoid point, the transformation temperature of a eutectoid, or the point representing it in a constitutional diagram.
B. n. A solid analogous to a eutectic, in which the high temperature phase is a solid solution instead of a liquid and the constituents separate out simultaneously when it is cooled to the transformation temperature.
1903H. M. Howe Iron, Steel, & Other Alloys 440 The word ‘eutectoid’ occurred to me (June 7, 1903)... It suggests having the shape or other important properties of the ‘eutectic’, while the two words differ from each other enough to indicate that they refer to really distinct things. 1910Encycl. Brit. XIV. 805/1 Excess of iron over this eutectoid ratio. Ibid., Far below the freezing-point, transformations may take place in the solid metal, and follow a course quite parallel with that of freezing, though with no suggestion of liquidity. A ‘eutectoid’ is to such a transformation in solid metal what a eutectic is to freezing proper. 1925Jrnl. Iron & Steel Inst. CXI. 584 The eutectoid occurring at 0·89 per cent. carbon theoretically should be regarded as a eutectoid of iron and a solid solution containing about 2·0 per cent of carbon. 1946Thorpe's Dict. Appl. Chem. (ed. 4) VII. 596/2 In this case..it is the solid solution beta breaking down into the two solutions alpha and gamma, and the point P is known as a eutectoid point. 1950Engineering 15 Dec. 492/3 Austenite in a plain eutectoid steel could decompose isothermally. 1961J. N. Anderson Appl. Dent. Mat. (ed. 2) vi. 56 One such reaction..is known as a eutectoid reaction. This involves the breakdown as a solid solution at a definite temperature to produce an intimate mechanical mixture of two solids. |