Brittle-to-ductile transition temperature in InP

Deformation experiments were conducted on monocrystalline InP by 4-point bend tests as well as by conventional and depth-sensing indentation (DSI) tests. Temperature ranges where the material exhibited a brittle or a ductile behavior were investigated with particular focus on the transition from one deformation mode to the other. The 4-point bend tests show that InP exhibits a sharp brittle-to-ductile transition (BDT) temperature within 5° between 350 and 355 °C at a strain rate of 2.9 × 10−5 s−1. The indentation BDT (IBDT) temperature is found to be significantly lower at ∼250 °C. The difference of nearly 100 °C between the two techniques is attributed to the hydrostatic component of the indentation stress field that suppresses fracture and shifts the transition to a lower temperature.