The Research On Deformation Behavior Of Zr-based Bulk Amorphous Alloys At Room Temperature And High Temperature

In this paper,the effects of deformation conditions such as aspect ratio and strain rate on the compression properties of Zr-based amorphous alloy are analyzed?The alloy specimens were subjected to a high temperature compression test by means of a thermal simulator to analyze the high temperature rheological properties of Zr-based amorphous alloy.Zr based amorphous alloy with trace rare earth element Er was prepared,different loading rates and holding times were selected,and the nanomechanical test system was used to test the mechanical properties of nano-indentation of the alloy specimens at room temperature.The following conclusions are drawn respectively:?1?This study indicates that the strain rate does not have a significant effect on the yield strength of Zr-based amorphous alloys.When the strain rate was 1 10-5s-1,the alloy specimen showed excellent mechanical properties,with plastic strain of10.5%,fracture strength of 1999 MPa and compressive strength of 2002 MPa.With the increase of strain rate,the plastic strain of alloy specimen decreased from 10.5%to 4.1%.At the same time,the compressive strength of alloy sample gradually decreased from 2001 MPa to 1767 MPa.The compressive plasticity of Zr-based amorphous alloy at room temperature is negatively correlated with the aspect ratio.When the aspect ratio is 1:1,the mechanical properties of alloy specimens are the best,the plastic strain is 26%,and the compressive strength is 2381 MPa.The fracture strength is 2375 MPa.The plastic strain of alloy specimen has a negative correlation with the aspect ratio of alloy specimen.As the aspect ratio increases,the plastic strain decreases from 26%to 2%.Meanwhile,the compressive strength of alloy specimen also decreased from 2381 MPa to 1741 MPa.On the other hand,the elastic modulus of alloy specimen is positively correlated with the aspect ratio.The larger the aspect ratio,the larger the elastic modulus of alloy specimen.?2?The flow stress of Zr-based amorphous alloy is greatly affected by temperature and strain rate,when the temperature of alloy specimen is increased or strain rate is decreased,the flow stress of alloy specimen tends to decrease.Specifically,when the deformation condition is 723 K⁵×10^-4s^-1,the minimum flow stress is 33.11 MPa;when the deformation condition is 678 K¹×10^-22 s^-1,the maximum flow stress is 652.59 MPa.The viscosity coefficient of the alloy specimen varies from 10¹11 Pa·s to 10⁹ Pa·s.From the comparison results of energy dissipation diagram and rheological instability diagram,the optimal hot working area of Zr-based amorphous alloy is mainly divided into two parts:?1 the area that with a low strain rate and the region of processing temperature is 678 K⁷08 K;?2the area that with a high strain rate and the processing temperature is 708 K⁷23 K;?3?The results of nano-indentation indicated that the creep displacement of the alloy specimen increased from 11.8 nm to 21.6 nm with the gradual increase of indentation loading rate.When the loading rate is increased,the nanoindentation hardness?H?and reduced elastic modulus?E_r?of alloy specimen show a decreasing trend.H decreased from 4.78 GPa to 4.35 GPa,and E_r decreased from 56.68 GPa to52.1 GPa.On the other hand,when the holding time is extended,the creep displacement is increased from 9 nm to 23 nm.At the same time,H decreased from4.78 GPa to 4.2 GPa,and E_r decreased from 54.66 GPa to 44.14 GPa.The alloy specimen has a sawtooth rheological phenomenon during the indentation loading phase.The lower the loading rate,the more obvious the sawtooth rheological phenomenon.The strain rate during creep deformation of the alloy specimen is positively related to loading rate during loading phase.