Hot Deformation Behaviour and Deformation Microstructure of an Al-Zn-Ce Damping Alloy

A damping alloy with a nominal composition of 50Al-49.9Zn-0.1Ce (at%) was tested in hot compression (60% depression) using a Gleeble-3800 thermomechanical simulator at deformation temperatures and strain rates ranging from 573 to 648K and 0.01 to 10 s(-1), respectively. According to the true stress-strain curves, two constitutive equation models based on peak stress and strain compensation were constructed. The microstructure of the alloy after deformation was characterized and analyzed by means of X-ray diffractometer (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The results show that the flow stress increases with decreasing deformation temperature and increasing strain rate. The theoretical predictions of the constitutive equation model at low temperature and high strain rate are well fitted to the measured values with low average absolute relative errors. At low strain rates and high temperatures, the alpha + eta eutectoid structure tends to transform from lamellar to granular morphologies, which is accompanied by the increased sizes of alpha and eta phases. Also, the obvious dissolution of eta into alpha phase has been occurred and some tiny holes induced by thermal-force coupling have been formed during compression. In this work, the Al-Zn-Ce damping alloy is more suitable for thermomechanical processing at relatively lower temperatures and meanwhile higher strain rates (such as at 573K/0.1 s(-1), 573K/10 s(-1) and 623K/10 s(-1)).