AgAu Alloys with Adjustable Thermal Expansion Properties
Original Publication Date: 1995-Aug-01
Included in the Prior Art Database: 2005-Mar-30
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).