Microstructural refinement of cast p-type Bi2Te3–Sb2Te3 by equal channel angular extrusion

Abstract The objective of this work was to develop a fine and homogeneous microstructure in cast p-type Bi2Te3–Sb2Te3 using multi-pass equal channel angular extrusion (ECAE). The ranges of independent extrusion variables examined were 450–525 °C, extrusion temperature; 0.25–7.5 mm/min, punch speed; and one (route A), two (route B and C), and four (route C and E) consecutive extrusion passes, corresponding to strain of 1.16–4.64. The microstructure was characterized by polarized optical microscopy. Recrystallized grains between 10 and 30 μm in size were achieved via four passes following a new extrusion route schedule (route E) at an extrusion temperature of 500 °C and a punch speed of 2.5 mm/min. Results indicate that ECAE processing is a viable method for grain refinement of cast intermetallic compound materials.