Strengthening retention and structural stability of the Al-Al3Ni eutectic at high temperatures

A sharp difference was revealed between strengthening retention of the Al-Al3Ni eutectic at temperatures up to 500 degrees C and room-temperature strengthening recovery after high-temperature exposures. Although the Al3Ni fibers exhibited high coarsening resistance that led to a remarkable recovery of about 80% of the eutectic yield stress after 1 week exposure at 500 degrees C, they were ineffective in retaining the strength at high temperatures that at 500 degrees C reached only 20% of the room-temperature level; the same retention ratio as for the identically-deformed pure aluminum that resembled the eutectic composite matrix. During uniaxial compression at 400-500 degrees C, the steady-state flow stress with negligible work hardening rate developed for both the eutectic and pure aluminum. The Al3Ni fibers did not act as potent nuclei towards promoting the dynamic recrystallization, resulting in dynamic recovery being the only microstructure restoration mechanism during hot deformation.

Automated summary

Although Al3Ni fibers exhibit high coarsening resistance at high temperatures, they are ineffective in retaining strength, only maintaining 20% of room-temperature level at 500 degrees Celsius. During uniaxial compression at 400-500 degrees Celsius, both eutectic and pure aluminum show steady-state flow stress with negligible work hardening rate.