Accession Number : AD0819810

Title :   TERNARY PHASE EQUILIBRIA IN TRANSITION METAL-BORON-CARBON SILICON SYSTEMS. PART II. TERNARY SYSTEMS. VOLUME XV. CONSTITUTION OF NIOBIUM-MOLYBDENUM-CARBON ALLOYS.

Descriptive Note : Technical rept.,

Corporate Author : AEROJET-GENERAL CORP SACRAMENTO CA MATERIALS RESEARCH LAB

Personal Author(s) : Rudy, Erwin ; Brukl, Charles E. ; Windisch, Stefan

Report Date : JUL 1967

Pagination or Media Count : 67

Abstract : The ternary alloy system niobium-molybdenum-carbon was investigated by means of X-ray, melting point, DTA, and metallographic techniques; a complete phase diagram for temperatures above 1500 C was established. Above 1960 C, niobium monocarbide and the cubic (B1) high temperature phase in the molybdenum-carbon system form and uninterrupted series of solid solutions. Six isothermal reactions occur in the ternary system; three correspond to class II-type four-phase reactions involving a liquid phase, one to a class I (eutectoid)-type, and two further isotherms are associated with limiting tie lines. The results of the phase diagram investigation are discussed, and the thermodynamic interpretation identifies the low relative stability of the binary subcarbides in conjunction with the large stability differences between niobium and molybdenum carbides as the cause for the formation of a stable equilibrium between the monocarbide and the metal phase in the ternary region.

Descriptors :   (*NIOBIUM ALLOYS, CARBIDES), (*MOLYBDENUM ALLOYS, CARBIDES), (*CARBIDES, PHASE DIAGRAMS), CHEMICAL EQUILIBRIUM, PHASE STUDIES, CARBON ALLOYS, X RAYS, MELTING POINT, DIFFERENTIAL THERMAL ANALYSIS, METALLOGRAPHY, SOLUBILITY, STABILITY, THERMOCHEMISTRY, DECOMPOSITION, VISUAL INSPECTION, CRYSTAL STRUCTURE, CHEMICAL ANALYSIS.

Subject Categories : Properties of Metals and Alloys

Distribution Statement : APPROVED FOR PUBLIC RELEASE