Effect Of Annealing And Compression On Hardness And Electronic Work Function Of Bulk Metallic Glass

Go with the development and progress of technology and industry, bulk metallic galss (BMGs) which provided with a unique atomic structure is studied by more and more material scholars by its excellent performance and good prospects. But its brittleness and the difficult to preparation limit its wide application seriously. In our studies, the electronic work function (EWF) of the amorphous alloys which treated by low temperature heat treatment and compression were tested by scanning Kelvin probe (SKP) technique. We analyzed the variety of the EWF and hardness of the BMGs with the aim of investigating their structure and mechanical behavior by a electronic scale and learn more about the unique microstructure to overcome its shortcomings in manufacturing and application. The main contents of this paper are as follows:1. Zr_41.2Ti_13.8Cu_12.5Ni₁₀Be_22.5 amorphous alloy samples were prepared by tungsten vacuum melting technique and vacuum copper mold suction casting, and heat-treated by different annealing time and temperature. After XRD, DSC and SEM tests we found that the glass transition temperature (Tg) is 623K, the crystallization temperature (Tx) is 703K and the super cooled liquid region is about 80K. And we found that the crystallization has not took place of the annealed Zr_41.2Ti_13.8Cu_12.5Ni₁₀Be_22.5 samples and there was a structural relaxation compared with the as-cast sample.2. We tested the EWF of the Zr_41.2Ti_13.8Cu_12.5Ni₁₀Be_22.5 amorphous alloy samples which were treated by low temperature heat treatment for different annealing time. The results showed that the values of the EWF decreased with the increasing of the annealing time.3. We also tested the EWF of the Zr_41.2Ti_13.8Cu_12.5Ni₁₀Be_22.5 amorphous alloy samples which were treated by different annealing temperatures. And the values of the EWF also decreased with increasing the annealing temperature. When the annealing temperature is closed to the glass transition temperature (Tg), the EWF was decreasing more obviously.4. The Rockwell hardness of the Zr_41.2Ti_13.8Cu_12.5Ni₁₀Be_22.5 amorphous alloy samples were tested and compared to the change of the value of EWF. It showed that the hardness and EWF values was changed in a inversely way which the hardness increased with the rise of the annealing temperature. We analyzed experimental results with the free volume model and the structural relaxation refer to the relative literatures.5. We tested the EWF of the Zr_41.2Ti_13.8Cu_12.5Ni₁₀Be_22.5 amorphous alloy samples which were compressed under different compression rate. The result shows that the values of the EWF increased when the compression rate rose. And we analyzed the result with the theory of free volume model.