Influence of CNTs and Ti on the microstructure and mechanical properties of W-based alloys

Abstract:

W-based alloys were fabricated at 1500℃ under a pressure of 25 MPa by high-energy ball milling and hot pressing，where the CNTs and Ti were used as the dopants．The influence of different dopants on the sintering density，morphologies and mechanical properties of sintered W-based materials was investigated. The microstructure was characterized by scanning electron microscopy (SEM) with energy dispersive spectrometer (EDS). The fracture strength and toughness were measured by three-point bending and single-edge notched beams tests, respectively. Density measurements indicated that both CNTs and Ti can effectively enhance the sintering behavior. The W-0.1CNTs and W-5Ti exhibited a high relative density of 95.8％ and 96.5％, but their grain size is large. In case of W-5Ti-0.1CNTs alloy, the density is high and the addition of CNTs and Ti can refrain the grain size. W-5Ti-0.1CNTs alloy showed the excellent mechanical properties. The microhardness, fracture strength and fracture toughness of W-5Ti-0.1CNTs alloy are 7.32GPa, 654.3MPa, 10.13MPa?m1/2. The microstructure analysis of fracture surface revealed that the intergranular fracture is the main mode for the W-0.1CNTs and W-5Ti alloys, but the W-5Ti-0.1CNTs fractured in a mixture mode of intergranular and transgranular fracture. These results demonstrated that both the addition of CNTs and Ti can refine the microstructure and enhance the strength and fracture toughness of W-based alloys.

Key words:W;W-based alloy;CNTs;high-energy ball milling;hot pressing