TRANSFORMATION MECHANISMS IN HYPOEUTECTOID AND HYPEREUTECTOID TITANIUM- CHROMIUM ALLOYS. Period covered: January 1, 1957 through December 31, 1957
A detailed morphological study has been made of the proeutectoid TiCr/ sub 2/ and eutectoid reactions in a spongebase Ti-- 17.42% Cr alloy isothermally transformed at temperatures from 775 through 550 deg C. The morphologies of proeutectoid TiCr/sub 2/ were shown to be subject to description by the Dube morphological classification system. Grain-boundary allotriomorphs are the dominant proeutectoid morphology throughout the temperature range investigated. Intragranular plates, and especially Widmanstatten side-plates, form only in small numbers. Idiomorphs were found, also in limited numbers, both intragranularly and at the grain boundaries. This morphological pattern differs markedly from that of the proeutectoid alpha reaction, as prevlously observed in hypoeutectoid Ti--Cr alloys, in which plates form prolifically throughout wide temperature ranges. The eutectoid reaction is non-llamellar in character at 675 deg C. An increasingly prominent pearlitic component develops at lower temperatures. Both eutectoid alpha and eutectiod TiCr/sub 2/ precipitate largely, if not entirely, from beta. The morphologies of proeutectiod alpha were studied in an iodide Ti-10.8% Cr alloy and were found to be essentially the same as those formed at temperatures 50 to 75 deg C higher in an iodide Ti-7.22% Cr alloy. This difference corresponds roughly to the 50 deg C difference in the transus temperatures of the two alloys. The eutectoid reaction in the Ti-10.8% Cr alloy was found to be entirely of the nonlamellar type. The beta phase was completely decomposed to proeutectoid alpha and eutectoid structure in the temperature range 625 deg C through 550 deg C, providing good evidence that the eutectoid temperature of the titanium-chromium system lies at a higher temperature, rather than in the vicinity of 500 deg C. (auth)
- Research Organization:
- Carnegie Inst. of Tech., Pittsburgh
- DOE Contract Number:
- AF33(616)-3969
- NSA Number:
- NSA-12-006615
- OSTI ID:
- 4309338
- Report Number(s):
- WADC-TR-57-709; AD-142175
- Resource Relation:
- Other Information: Project title: SOLID STATE RESEARCH AND PROPERTIES OF MATTER. Task title: PHASE RELATIONSHIPS IN METALLIC AND CERAMIC SYSTEMS. Orig. Receipt Date: 31-DEC-58
- Country of Publication:
- United States
- Language:
- English
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