Abstract:Effects of cooling rate on thermal expansion of Cu₄₉Hf₄₂Al₉ metallic glass were studied. Five types of amorphous samples with different sizes were prepared in order to get a broad range of cooling rates (from 10² to 10⁷ K/s). The average thermal expansion coefficients (α_aver) of as-quenched samples range from 6.14×10⁻⁶ to 9.20×10⁻⁶ K⁻¹. When the temperature is below the glass transformation temperature (T_g), α_aver of as-quenched samples has a negative correlation with cooling rate; the values of α_aver of annealed and crystallized samples are closed to each other. The results indicate that the amount and motion of free volume play important roles in thermal expansion of metallic glasses.

Key words: metallic glass; thermal expansion; cooling rate