Electron Backscattered Diffraction of Aluminium Alloy 7075 Samples after Heat Treatment

The RAP process (Recrystallisation And Partial melting) is a reheating route used to give shear-thinning and thixotropic behaviour to a billet of semi-solid material. This process uses the recrystallisation phenomenon to obtain globular solid grains surrounded by a liquid matrix. Recrystallisation of rolled 7075 aluminium alloys in the T6 condition is difficult because dispersoid particles pin the grain boundaries. Here we examine with Electron Backscattered Diffraction the presence of intermetallic phases in the structure after reheating to various temperatures in the semi-solid range and quenching. The presence of these particles could explain some of the microstructural behaviour at semisolid temperatures. In addition, EBSD is used to examine whether recrystallisation has occurred.