Effect of Annealing on Microstructure and Microhardness of Melt-Spun Al–20Si–5Fe Ribbons

Rapid solidification process provides a typical case of non-equilibrium solidification, hence refines significantly the microstructural features (grain size and size of second phase/intermetallic particles), reduces segregation effects, increases the solid solubility extension and induces constitutional changes in alloys (formation of supersaturated solid solutions, metastable crystalline intermediate, and amorphous phases). The present study is concerned with the effect of annealing on microstructure and microhardness of rapidly solidified ternary Al–20Si–5Fe alloy at cooling rates between 106 and 107 K/s using the melt spinning technique. The melt spun ribbons characterized using X-ray diffractometry and scanning electron microscopy. The obtained results demonstrated the size of primary silicon, the intermetallic phases, and the eutectic silicon in the melt-spun ribbons were extremely modified as compared with those found in conventionally processed materials. Annealing at various temperatures from 200 to 450○C for a specific time disclosed that the two predetermined zones can’t be distinguished after heat treatment. Also, increasing of the temperature reduced the microhardness. Furthermore, the solid solubility levels of alloying elements (Si and Fe) in Al substantially increased which resulted in solid solution strengthening.

کلیدواژه ها:

Al-20Si-5Fe alloy ، Rapid solidification Process ، Melt-Spinning ، Microstructure ، Microhardness ، Annealing