Continuous extrusion is a very promising technique for forming Cu–Cr–Zr alloys which takes the upward continuous casted rods as raw materials. While the hot deformation behavior and constitutive equation of as-cast rods have never been reported. In the present study, the hot deformation behavior of as-cast Cu–Cr–Zr rods with columnar grains was investigated. The results showed that the flow stress at 500 °C is higher than that at 400 °C. The reason for that can be attributed to the dynamic precipitation process, which was confirmed by TEM observations. At this temperature, partial CDRX dominates the softening mechanism while at high temperatures DRV and DDRX play a critical role. The constitutive equation was then established and the deformation activation energy was determined to be 541.93 kJ/mol. The high activation energy was attributed to the large solidified columnar grains. At high strains, stable metal flows can be obtained at high strain rates and high temperatures according to the processing maps, which indicates that a high-speed deformation at a high temperature is favorable to the plastic forming of this material. This investigation thus provides valuable information on how to process the Cu–Cr–Zr rods by plastic deformation methods, for example, continuous extrusion.

Graphical Abstract

中文翻译：

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上向连铸Cu-Cr-Zr棒的热变形行为及本构方程

连续挤压是一种非常有前途的以向上连铸棒材为原料形成Cu-Cr-Zr合金的技术。而铸棒的热变形行为和本构方程尚未见报道。在本研究中，研究了柱状晶铸态 Cu-Cr-Zr 棒的热变形行为。结果表明，500℃时的流变应力高于400℃时的流变应力。其原因可归因于动态沉淀过程，TEM 观察证实了这一点。在此温度下，部分 CDRX 在软化机制中占主导地位，而在高温下 DRV 和 DDRX 则发挥关键作用。建立本构方程，确定变形活化能为541.93 kJ/mol。高活化能归因于大的凝固柱状晶粒。根据加工图，在高应变下，在高应变率和高温下可以获得稳定的金属流动，这表明高温下的高速变形有利于该材料的塑性成形。因此，这项研究为如何通过塑性变形方法（例如连续挤压）加工 Cu-Cr-Zr 棒提供了有价值的信息。

图形概要