CAJ | 학술논문

通过2道次往复挤压制备细晶ZK60合金,在443～523 K和初始应变速率为3.3×10-4～3.3× 10-2 s-1的范围内测试合金的低温超塑性.结果表明:往复挤压ZK60合金的平均晶粒尺寸约为5.0 μm,分布于基体内的破碎二次相颗粒和沉淀颗粒尺寸分别为不大于175 nm和50 nm.该合金具有低温准超塑性,在523K和3.3×10-4 s-1应变速率下伸长率最大,为270％;在443和473 K时,应变速率敏感系数m小于0.2;在523 K时m为0.42.当温度不高于473 K和523K时,超塑性变形激活能分别不高于63.2 kJ/mol和110.6 kJ/mol.当低于473K时,主要的超塑性流变机制为晶内滑移;在523K时,主要的超塑性变形机制为晶界滑移,由晶界扩散控制的位错蠕变为主要的兼容机制.
통과2도차왕복제압제비세정ZK60합금,재443～523 K화초시응변속솔위3.3×10-4～3.3× 10-2 s-1적범위내측시합금적저온초소성.결과표명:왕복제압ZK60합금적평균정립척촌약위5.0 μm,분포우기체내적파쇄이차상과립화침정과립척촌분별위불대우175 nm화50 nm.해합금구유저온준초소성,재523K화3.3×10-4 s-1응변속솔하신장솔최대,위270％;재443화473 K시,응변속솔민감계수m소우0.2;재523 K시m위0.42.당온도불고우473 K화523K시,초소성변형격활능분별불고우63.2 kJ/mol화110.6 kJ/mol.당저우473K시,주요적초소성류변궤제위정내활이;재523K시,주요적초소성변형궤제위정계활이,유정계확산공제적위착연변위주요적겸용궤제.
Fine-grained ZK60 alloy was prepared by 2-pass reciprocating extrusion,and the low temperature superplasticity was conducted in a temperature range from 443 to 523 K and an initial strain rate ranging from 3.3×10 4 to 3.3×10-2 s-1.The results show that the alloy has an equiaxed grain structure with an average grain size of about 5.0 μm,and the sizes of broken secondary particles and precipitates are no more than 175 and 50 nm,respectively.The alloy exhibits quasi-superplasticity with a maximum elongation of 270％ at 523 K and an initial strain rate of 3.3×10-4 S-1.The strain rate sensitivity m is less than 0.2 at 443 and 473 K,and it is 0.42 at 523 K.The apparent activation energies at temperature below 473 K and at 523 K are less than 63.2 and 110.6 kJ/mol,respectively.At temperature below 473 K,mainly intragranular sliding contributes to superplastic flow.At 523 K,grain boundary sliding is the dominant deformation mechanism,and dislocation creep controlled by grain boundary diffusion is considered to be the main accommodation mechanism.