High strain rate superplasticity at intermediate temperatures of the Al 7075 alloy severely processed by equal channel angular pressing

作者：Cepeda Jimenez C M; Garcia Infanta J M; Ruano O A; Carreno F^*

来源：Journal of Alloys and Compounds, 2011, 509(40): 9589-9597.

DOI：10.1016/j.jallcom.2011.07.076

• Al-Zn-Mg-Cu alloy
• ECAP
• Superplasticity
• Deformation mechanisms
• Microstructure

The mechanical properties of an overaged Al 7075-O alloy processed by ECAP were examined by tensile tests at intermediate-high temperatures ranging from 250 to 400 degrees C and strain rates from 10(-5) to 10(-1) s(-1). The influence of the number of ECAP passes on the ductility enhancement was evaluated. Elongation to failure, e(F), significantly increased with increasing the number of ECAP passes up to 8 at 130 degrees C. The alloy processed under these conditions exhibited a maximum value of 322% at 300 degrees C and an initial strain rate of 10(-3) s(-1). High strain rate, e(F) = 210%, at a strain rate as high as 10(-2) s(-1). The large elongations together with lower stresses and lower stress exponents than those for the start material confirm that grain boundary sliding (GBS) is the operative deformation mechanism. A loss of superplastic behaviour at temperatures above 350 degrees C is related to abnormal grain growth and a change of deformation mechanism.

• 出版日期2011-10-6