Abstract
Herein, we propose an experimental method based on the Barandiaran–Colmenero relation for evaluating the critical cooling rate (Rc) of Pd82Si18 amorphous ribbon. In this method, to determine the inherent Rc of glass ribbon, heterogeneous nucleation is suppressed during the differential scanning calorimeter measurement process by adding soda lime flux. The Rc values of Pd82Si18 amorphous ribbon were determined before and after soda lime treatment. The experimental results indicate that the Rc values of the treated and non-treated ribbon are 10.27 and 148.39 K/s, respectively. The Rc value of the treated sample is in good agreement with a previous experimental result. Johnson’s relation gives Rc = 22.86 K/s, which confirms the validity of the present results. The results indicate that soda lime flux greatly suppresses heterogeneous nucleation during the measurement process and the inherent Rc of Pd82Si18 is revised. This method provides a new way for evaluating the critical cooling rate by suppressing heterogeneous nucleation.
Highlights
The critical cooling rate (Rc) of an alloy upon solidification, which is defined as the minimum cooling rate to form a fully amorphous structure without detectable crystallization, is an indispensable indicator for assessing the glass forming ability (GFA) of amorphous materials
We have investigated the effect of soda lime treatment on the critical cooling rate of Pd82Si18 amorphous ribbon
The main findings are as follows: (1) The Rc values for treated and non-treated Pd82Si18 ribbon samples are 10.27 and 148.39 K/s, respectively, and the decrease in Rc is in good agreement with previous experimental results
Summary
The critical cooling rate (Rc) of an alloy upon solidification, which is defined as the minimum cooling rate to form a fully amorphous structure without detectable crystallization, is an indispensable indicator for assessing the glass forming ability (GFA) of amorphous materials. By measuring T l upon melting at a constant heating rate and T xc upon cooling at different cooling rates by DSC, the critical cooling rate for glass formation can be determined from the plot of ln R against 1000/(T l T xc)[2] This method has been widely used to determine the critical cooling rates of bulk metallic glasses[2,3] and lithium silicate glass.[4] It should be noted that this measurement process requires glass ribbon to be placed in a crucible upon heating and cooling. It has been reported that the critical cooling rate is strongly dependent on the ease of heterogeneous
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