A Method for Testing Dynamic Mechanical Behavior of Materials at Ultra-High Temperature and in-Situ Observation

In this work, we propose a novel method for testing the dynamic mechanical properties of materials and for in-situ observation at ultra-high temperature (up to 1 600 ℃).The experimental devices used include a classical split Hopkinson pressure bar, a MoSi₂ heating source for obtaining ultra-high temperature, two piston rods added to complement the double synchronically assembled system and a high speed camera employed to observe the deformation.To verify the ability of the proposed method for operating at ultra-high temperature, we conducted our experiments on TC4 alloy at temperatures ranging from 20 to 1 400 ℃ and the strain rate of 2 000 s^-1, and SiC at temperatures ranging from 20 to 1 200 ℃ and the strain-rate of 250 s^-1.The results showed that the peak flow stress of the TC4 alloy specimen drops from 1.6 GPa at room temperature to 150 MPa at 1 400 ℃, and the compressive strength of the SiC specimen drops from 250 MPa at room temperature to 220 MPa at 1 200 ℃.Furthermore, the high speed images revealed that the oxide layer of the TC4 alloy specimen cracked in air but not in argon, and the initial cracks of the SiC specimen occurred at 80% of the compressive strength at room temperature and at 99% of the compressive strength at 1 200 ℃.