Abstract: Super-cooled liquid region, time-temperature-transformation diagram, and mechanical behavior of Zr41.25Ti13.75Ni10Cu12.5Be22.5 in the super-cooled liquid region were investigated , and based on which , precision cams are fabricated by using die forging method. The effects of different temperatures and different strain rates on the formability were analyzed. The results show that Zr41.25Ti13.75Ni10Cu12.5Be22.5 bulk amorphous alloy exhibits a good superplasticity formability in the super-cooled liquid region of 635.6-710.4K with the strain rate sensitivity exponent m-value being approximately 1.0. The acceptable temperature and strain rate range for superplastic forming of this material are 653 -668K and 5.0×10-4 -5.0×10-3 s-1 respectively. Under the processing conditions of 668K and 5.0×10-4s-1, the incubation time for retaining the glassy phase without decomposition reaches 1000s and the largest flow stress is less than 70 MPa.
Superplastic forming properties of Zr-based bulk amorphous alloys
Abstract:
Super-cooled liquid region, time-temperature-transformation diagram, and mechanical behavior of (Zr41.25Ti13.75)Ni10Cu12.5Be22.5 in the super-cooled liquid region were investigated , and based on which , precision cams are fabricated by using die forging method. The effects of different temperatures and different strain rates on the formability were analyzed. The results show that Zr41.25Ti13.75Ni10Cu12.5Be22.5 bulk amorphous alloy exhibits a good superplasticity formability in the super-cooled liquid region of 635.6710.4 K with the strain rate sensitivity exponent m-(value) being approximately 1.0. The acceptable temperature and strain rate range for superplastic forming of this material are 653 668 K and 5.0×10-4 5.0×10-3 s-1 respectively. Under the processing conditions of 668 K and 5.0×10-4 s-1, the incubation time for retaining the glassy phase without decomposition reaches 1 000 s and the largest flow stress is less than 70 MPa.
图3 Zr41.25Ti13.75Cu12.5Ni10Be22.5大块 非晶合金不同温度下的应力—应变曲线 Fig.3 True stress—strain curves of Zr41.25Ti13.75Cu12.5Ni10Be22.5 bulk metallic glass at different temperature
图4 Zr41.25Ti13.75Cu12.5Ni10Be22.5大块 非晶合金在不同应变速率下的应力—应变曲线 Fig.4 True stress—strain curves of Zr41.25Ti13.75Cu12.5Ni10Be22.5 bulk metallic glass under different strain rates 1—1.0×10-4 s-1; 2—1.0×10-2 s-1; 3—5.0×10-3 s-1; 4—5.0×10-4 s-1; 5—1.0×10-3 s-1
图5 Zr41.25Ti13.75Cu12.5Ni10Be22.5大块 非晶合金在不同应变速率下的时间—应变曲线 Fig.5 Time—strain curves of Zr41.25Ti13.75Cu12.5Ni10Be22.5 bulk metallic glass at different strain rates