Tensile Deformation Behavior of Al-Cu 206 Cast Alloys near the Solidus Temperature

Abstract

To study the micromechanics of semisolid deformation, a modified experimental set-up is employed in Gleeble 3800 thermomechamical testing unit to achieve a uniform temperature distribution in partially remelted aluminum samples. The temperature variation was markedly reduced to one degree for a length of 4-5 mm in the middle of tensile samples. High temperature semisolid tensile tests of Al-Cu 206 cast alloys were performed at different temperatures near solidus with a strain rate of 10-3 s-1, corresponding to the solid fractions (fs) between 1 and 0.95. The stress-displacement curves with different fs were measured and analyzed. The microstructure and fracture surface of samples were examined by optical and scanning electron microscopes. The relation between the microstructural characteristics, tensile properties and fracture behavior of semisolid 206 samples at high fs were explored. Mush deformation mechanisms were discussed in term of defect nucleation and propagation at the late stage of solidification.

Effect of Fe-Rich Intermetallics on Tensile Behavior of Al–Cu 206 Cast Alloys at Solid and Near-Solid States

“…%) within the mush structure determines the tensile strength of the semi-solid castings [14,15]. If the liquid can easily flow within the mush structure and feed the regions which are being tensile deformed, the structure can accommodate more deformation until the fracture failure [12]. Therefore, the significant difference in displacement for the two experimental alloys is also expected to be related to the variations in the flow of liquid during deformation caused by the different intermetallic compounds present in experimental alloys.…”

“…Recently, the near-solid tensile testing method has been well developed to simulate the stress-strain conditions during solidification of aluminum alloys [11,12], providing a practical approach to investigate the influence of Fe-rich intermetallics on the hot-tearing susceptibility.…”

Archives of Metallurgy and Materials

“…Iron is an element with a negative effect on Al-Cu alloys. This is mainly due to the shape of the phases that it forms [8,9]. Phases rich in iron (β-Fe) in plate form are more unfavorable than those occurring as compact phases or in the form of so-called Chinese writing [9].…”

“…The current literature data provides information on the topicality of the issue taken up in the research on the phase shaping and strengthening of the 2xx group alloys' [3,8,9] microporo sity [4] and crystal growth restriction GRF (Growth Restriction Factor), among others [10,11].…”