Microstructure And Compressive Properties At Room Temperature Of (Ti₅₁Zr₂₅Cu₆Be₁₈)_100-xV_x Bulk-metallic-glass-matrix Composites By Semi-solid Isothermal Treatment

Compared with the corresponding monolithic bulk metallic glasses（BMGs）,the bulk metallic glass matrix composites（BMGMCs）have better plastic deformation ability and can be used as advanced structural materials in the engineering field.In this paper,Ti₄₅Zr₂₂V₁₂Cu₅Be₁₆ composites were designed by pseudo-ternary phase diagrams.And the Ti-based BMGMCs with five components(Ti₅₁Zr₂₅Cu₆Be₁₈)_100-xV_x series were designed by changing the content of V elements.The as-cast specimens were prepared through using the copper mold suction casting method.The as-cast specimens were treated with semi-solid isothermal treatment.The specimens before and after the semi-solid isothermal treatment were characterized by metallographic microscopy,XRD,DSC and SEM.The compressive properties at room temperature were tested.The main conclusions are as follows:（1）The volume fraction ofβ-Ti phase of Ti-based BMGMCs developed by the copper mold suction casting decreases in the early time and then increases with the addition of V element.The addition of element V can refine theβ-Ti phase in the Ti-based BMGMCs.The addition of element V can improve the thermal stability of Ti-based BMGMCs,but slightly lower the glass forming ability of Ti-based BMGMCs.With the increase in the content of element V,the room-temperature compressive plastic strain of the Ti-based BMGMCs increases at first and then decreases,and the maximum plastic strain is 7.3%.（2）The composition of Ti-based BMGMCs phase is not changed by Semi-solid isothermal treatment.When samples were treated by different semi-solid isothermal treatments,the shape factor of theβ-Ti phase in the Ti₄₅Zr₂₂V₁₂Cu₅Be₁₆ composite materials reaches its maximum at 880°C for 3 min,which is 0.67.The kinetic factor K for the growth ofβ-Ti phase at this temperature is 0.13 um²/s,and the growth index n is 2.（3）When the isothermal treatment of Ti₄₅Zr₂₂V₁₂Cu₅Be₁₆ composite materials is conducted at 880°C for 3 min,the plastic strain reaches a maximum of 13.39%,and the plastic strain increases by 83.42%compared with the as-cast condition.It shows that the semi-solid isothermal treatment has obvious improvement on the plasticity of the BMGMCs.（4）After the(Ti₅₁Zr₂₅ Cu₆Be₁₈)_100-xV_x series of Ti-based BMGMCs samples isothermally treated at 880°C for 3 min,the shape factor of Ti₄₁Zr₂₀Cu₅Be₁₄V₂₀ is the largest,which is 0.72.The room temperature compressive plastic strain is still the largest component of Ti₄₅Zr₂₂V₁₂Cu₅Be₁₆.After the semi-solid isothermal treatment,the largest increase of the room temperature compressive plastic strain is Ti₄₁Zr₂₀Cu₅Be₁₄V₂₀,and the increase is 550%.