Flow behavior and microstructure of Co3Ti intermetallic alloy during superplastic deformation
Flow behavior and microstructure of Co3Ti intermetallic alloy during superplastic deformation
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DOI：
10.1016/s1359-6454(98)00029-9
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发表时间：
1998-06
期刊：
影响因子：
9.4
通讯作者：
W. Kim;S. Hanada;T. Takasugi
中科院分区：
文献类型：
--
作者：
W. Kim;S. Hanada;T. Takasugi
研究了L12型Co 3 Ti合金的超塑性变形行为，并通过流变行为、本构方程和变形组织对该合金的超塑性变形行为进行了表征。在较高的应变速率（也是较低的温度和较大的初始晶粒尺寸）区域，流变曲线呈现出应力峰值，随后应力迅速下降，并且发生动态再结晶（DRX）。该区域的变形激活能为Q= 158 kJ/mol，与体扩散激活能相近。这表明与DRX相关的机制是负责在这个区域的变形。在较低的应变速率区（较高的温度和较小的初始晶粒尺寸），流变曲线表现为连续的加工硬化直至断裂，并伴随着晶界滑移和晶粒长大的运动。该区域的变形激活能为Q= 80 kJ/mol，为晶界扩散激活能。在后一区域观察到大的拉伸延伸率，即超过200%的超塑性变形。这表明，晶界滑动机制是负责在这个区域的变形。
The superplastic deformation of the L12-type Co3Ti alloy was observed as functions of temperature, strain rate and initial grain size, and then characterized by the flow behavior, the constitutive equation and the deformation microstructure. In the region of higher strain rate (also lower temperature and larger initial grain size), the flow curve exhibited a stress peak followed by a rapid stress decrease, and dynamic recrystallization (DRX) occurred. The activation energy of deformation in this region was estimated to be Q=158kJ/mol, similar to that for the bulk diffusion. It is suggested that the mechanism associated with DRX is responsible for the deformation in this region. In the region of lower strain rate, (also higher temperature and smaller initial grain size), the flow curve exhibited continuous work hardening until fracture, and the concomitant motion of grain boundary sliding and grain growth occurred. The activation energy of deformation in this region was estimated to be Q=80kJ/mol suggestive of that of grain boundary diffusion. Large tensile elongation, i.e. superplastic deformation beyond 200% was observed in the latter region. It is suggested that the grain boundary sliding-based mechanism is responsible for the deformation in this region.