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AgAu Alloys with Adjustable Thermal Expansion Properties

IP.com Disclosure Number: IPCOM000116272D
Original Publication Date: 1995-Aug-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Shi, LT: AUTHOR [+2]

Abstract

According to the phase diagrams of Au-Ge and Ag-Ge, it is found that up to 3 at% Ge can be dissolved in Au at 361 degrees C and up to 9.6 at% Ge can be dissolved in Ag at 651 degrees C. Here both temperatures are eutectic ones. However, most Ge atoms precipitate out at room temperature after cooling. Since the Ge atoms in the precipitation state occupy a much larger volume than the Ge atoms in solution in either Au or Ag. Thus, the thermal expansion properties as a function of temperature of either Au or Ag can be adjusted by adding Ge atoms. Since Au and Ag form solid solution over the entire composition range, it is found that by adding Ag into Au the solubility of Ge in Au can be increased to a greater value than 3 at% (at a temperature higher than the Au-Ge eutectic temperature, i.e., gt361degreeC).

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AgAu Alloys with Adjustable Thermal Expansion Properties

      According to the phase diagrams of Au-Ge and Ag-Ge, it is found
that up to 3 at% Ge can be dissolved in Au at 361 degrees C and up to
9.6 at% Ge can be dissolved in Ag at 651 degrees C.  Here both
temperatures are eutectic ones.  However, most Ge atoms precipitate
out at room temperature after cooling.  Since the Ge atoms in the
precipitation state occupy a much larger volume than the Ge atoms in
solution in either Au or Ag.  Thus, the thermal expansion properties
as a function of temperature of either Au or Ag can be adjusted by
adding Ge atoms.  Since Au and Ag form solid solution over the entire
composition range, it is found that by adding Ag into Au the
solubility of Ge in Au can be increased to a greater value than 3 at%
(at a temperature higher than the Au-Ge eutectic temperature, i.e.,
gt361degreeC).  Therefore, the thermal expansion properties of Au-Ge
can be further adjusted to cover a wider range by forming Au-Ag
alloys.