Some physical properties of two amorphous metallic alloys

Abstract

Room‐temperature values of the thermal‐expansion coefficient, thermal diffusivity, thermal conductivity, density, Young's modulus E, and the temperature coefficient (1/E) dE/dT are presented for two splat‐cooled amorphous alloys of composition (in atomic percent) Pd₈₂Si₁₈ and Fe₇₅P₁₅C₁₀. Values of E were obtained from the flexural resonant frequencies of cantilever mounted reeds; the thermal properties were derived from internal friction measurements giving the height and location of the thermoelastic ``transverse thermal current'' peak. Compared to crystalline alloys, the amorphous samples are poorer thermal conductors but exhibit a comparable expansion behavior. In view of the small density difference between the amorphous and crystalline states, the most striking difference observed was the lower elastic modulus of the amorphous alloys. The present results supplement a growing body of evidence that materials in the amorphous condition may have a Young's or shear modulus which is typically 20–40% less than the value in the crystalline state.