Investigators: Ared Cezairliyan, Tsuyoshi Matsumoto, John McClure, and Louis Phillips

Technical Description:

This project is involved with the accurate determination of selected thermophysical properties of high temperature alloys of technological interest, particularly Ni-base superalloys important for the NIST Consortium on Casting of Aerospace Alloys. Millisecond- and microsecond- resolution pulse-heating techniques are used to make measurements in both solid and liquid phases up to about 300 K above their melting region. Work focuses primarily on measurements of selected key properties, such as enthalpy, specific heat, heat of fusion, electrical resistivity, hemispherical total emissivity, and normal spectral emissivity.

Technical Objectives:

• Obtain accurate thermophysical properties data on selected multicomponent alloys of technological interest, primarily those used in the aerospace industry, in support of modeling of casting processes.

• Develop methods of estimating properties of an alloy from the properties of its constituent elements.

• Obtain accurate thermophysical properties data on selected well-characterized binary and ternary alloys in support of validation of the estimation methods.

Anticipated Outcome:

• Generation of accurate thermophysical properties data on alloys needed by the casting industry.

• Development of reliable methods for estimating properties of multicomponent alloys from the properties of constituent elements.

Accomplishments for FY 1995:

• Preliminary measurements of the properties (enthalpy, specific heat, heat of fusion, electrical resistivity, and normal spectral emissivity) of a nickel-base alloy (Mar- M247) were made in both solid and liquid phases, extending to temperatures about 400 K above its melting region. This alloy is used for fabrication of blades in some jet engines.

• Dependence of the solidus temperature on heating rate of the binary alloy 53Nb-47Ti was studied over a ten-fold variation in the heating rate.

• The solidus temperature of the binary alloy 53Nb-47Ti was measured; the result indicates that the solidus curve in the phase diagram for this alloy, as generally accepted in the literature, is likely to be significantly low.

Impacts and Technical Highlights:

• NIST generated thermophysical properties data on selected alloys are used by key U.S. aerospace companies in modeling casting processes.

• Accurate data on solidus and liquidus temperatures have been used to improve the phase diagrams of some high-temperature alloys.

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Last modified: Mon Jan 06 09:46:15 1997 Metallurgy Webmeister