Fabrication of Ultra-Fine-Grained W-TiC Alloys by a Simple Ball-Milling and Hydrogen Reduction Method

Weixin Yu,Ningbo Sun,Zhijun Yang,Junhui Cao,Shusen Hou,Shaoting Lang

doi:10.3390/ma14195865

Abstract

In this paper, a simple method to fulfill the ideal microstructural design of particle reinforced tungsten (W) alloys with promising mechanical properties is presented. W-0.5 wt.% TiC powders with core-shell (TiC/W) structure are prepared by ball-milling and controlled hydrogen reduction processes. TEM observation demonstrates that the nano TiC particles are well coated by tungsten. The W-TiC powders are sintered by spark plasma sintering (SPS) under 1600 °C. The sintered microstructures are characterized by FESEM and TEM. It is found that the W-0.5TiC alloys obtain an ultra-fine-sized tungsten grain of approximately 0.7 μm. The TiC particles with the original nano sizes are uniformly distributed both in tungsten grain interiors and at tungsten grain boundaries with a high number density. No large agglomerates of TiC particles are detected in the microstructure. The average diameter of the TiC particles in the tungsten matrix is approximately 47.1 nm. The mechanical tests of W-0.5 TiC alloy show a significantly high microhardness and bending fracture strength of 785 Hv0.2 and 1132.7 MPa, respectively, which are higher than the values obtained in previous works. These results indicate that the methods used in our work are very promising to fabricate particle-dispersion-strengthened tungsten-based alloys with high performances.

Highlights

As a body-centered cubic metal, it is well known that tungsten shows brittle behavior at lower temperatures, especially below the ductile-brittle transition temperature (DBTT) [8,9]
200 nm, and the particles inclined to aggregate into larger particles
The prepared WO3 powders showed an irregular shape with particle sizes in the range of 20 to 300 nm

Summary

Introduction

Tungsten and its alloys have been used for many engineering applications such as in the aerospace, automotive, nuclear energy, materials processing, and defense industries. They are considered attractive materials for high-temperature applications such as heating elements, rocket nozzles, heat shields, and combustion chambers [1,2,3]. This is due to the superior properties of tungsten such as high melting point (3420 ◦ C), high thermal conductivity, high tensile strength, and high hardness [1,2,3,4,5]. Pure tungsten tends to crack more at room temperature than at temperatures higher than 400 ◦ C, which restricts its possible applications as structural materials

Methods

Results

Conclusion