Microstructure and High-Temperature Ablation Behaviour of Hafnium-Doped Tungsten-Yttrium Alloys

Abstract

W is a widely used refractory metal with ultra-high melting point up to 3410 °C. However, its applications are limited by poor ablation resistance under high-temperature flame and air flow, which is crucial for aerospace vehicles. To improve the ablation resistance of W under extreme conditions, W-Y alloys doped with different Hf mass fractions (0, 10, 20, and 30) were prepared using the fast hot pressing sintering method. Microstructure and ablation behaviours at 2000 °C were investigated. Results showed that adding an appropriate amount of Hf improved the properties of the W-Y alloy evidently. In particular, the hardness of the alloy increased with the increased content of Hf. The formation of the HfO2 layer on the surface during ablation decreased the mass and linear ablation rates, indicating enhanced ablation resistance. However, excessive Hf addition will result in crack behaviour during ablation. With a Hf content of 20 wt.%, the alloy exhibited high stability and an excellent ablation resistance.

High-Temperature Tribological Behavior of Fast-Hot-Pressed NiCr/Cr3C2-LaF3 Self-Lubrication Composite

“…The NiCr alloy is uniformly distributed throughout the bulk in a droplet-like form. Fast hot pressing sintering [29][30][31] enhances the sintering activity of Cr3C2 powder, enabling dense sintering at 1100 °C. Furthermore, the presence of the NiCr alloy phase significantly reduces porosity, resulting in a nearly fully dense block.…”

“…The NiCr alloy is uniformly distributed throughout the bulk in a droplet-like form. Fast hot pressing sintering [29][30][31] enhances the sintering activity of Cr 3 C 2 powder, enabling dense sintering at 1100 • C. Furthermore, the presence of the NiCr alloy phase significantly reduces porosity, resulting in a nearly fully dense block. Given this composite structure, we categorize its hardness into two distinct phases: a ceramic phase primarily composed of Cr 3 C 2 and LaF 3 , and a metal phase primarily constituted of the NiCr alloy.…”

Metallic Materials: Structure Transition, Processing, Characterization and Applications

“…Wu et al [ 26 ] contributed a paper entitled “Microstructure and High-Temperature Ablation Behaviour of Hafnium-Doped Tungsten-Yttrium Alloys”, in which it was found that the properties of the microstructure and high-temperature ablation behavior of hafnium-doped tungsten–yttrium alloy can be improved evidently by adding an appropriate amount of hafnium. The alloy exhibited high stability and excellent ablation resistance with a hafnium content of 20 wt.%.…”