Accession Number:

AD0662408

Title:

THE METASTABILITY OF GOLD-ANTIMONY PHASES PREPARED BY SPLAT COOLING

Descriptive Note:

Technical Report

Corporate Author:

MASSACHUSETTS INST OF TECH CAMBRIDGE CAMBRIDGE

Report Date:

1967-11-15

Pagination or Media Count:

19.0

Abstract:

The metastable gold-antimony phases zeta containing 15.0 at. pct Sb and pi containing 76.6 pct Sb were prepared by splat cooling. The heats of formation of these phases were measured by solution calorimetry and their free energies of formation were estimated. An analysis of the free energies of the relevant phases leads to the following conclusions. 1 The phases zeta and pi are unstable at all temperatures. 2 Liquid alloys containing 15.0 pct and 76.6 pct Sb, respectively, must be undercooled by at least 150 deg and 200 deg K for the phases zeta and pi to form. 3 The temperature below which the pi phase can form 600 deg K is about 250K lower than the temperature below which the zeta phase can form. 4 Although the free energies indicate that the pi phase is more unstable than the zeta phase, the calculated degrees of undercooling required and the calculated temperature of formation of the two phases indicate that the pi phase is less difficult to produce by splat cooling than the zeta phase. This is in agreement with experimental observations.

Subject Categories:

Distribution Statement:

APPROVED FOR PUBLIC RELEASE