Solidified Structures of Al-Ti Peritectic System Alloys under Microgravity Conditions

Abstract

In order to clarify the solidification mechanisms of Al-Ti and Al-Ti-B system alloys under microgravity conditions, experiments are carried out by using Sounding Rocket TR-lA No. 6. Different compositions of six samples are melted and solidified in the two isothermal furnaces on board the rocket. In the higher temperature furnace of 1400°C, the hyper-peritectic composition of Al-1.3%Ti alloy revealed that the primary TiAl3 crystals distributed in the melt act as nucleation sites and then form granular crystals. The hypo-peritectic alloy revealed that the TiAh and TiB2 crystals in the Al-Ti and Al-Ti-B master alloys are melted perfectly and then the large crystals form. In the lower temperature furnace of B00°C, TiAh and TiB2 crystals in the master alloy remained and they nucleated the granular crystals as if the peritectic reaction occurred.