Selective laser melting of lanthanum oxide-reinforced tungsten composites: microstructure and mechanical properties

Abstract

In this study, La 2 O 3 nanoparticles were introduced into the tungsten (W) matrix to optimize the microstructure and properties of pure W. The W-La 2 O 3 composites with different mass ratios of La 2 O 3 were manufactured by selective laser melting (SLM). The result showed that the average grain sizes for W-1 wt% La 2 O 3 and W-2 wt% La 2 O 3 were reduced by more than 51.3% compared with that of pure W, and the defects obviously decreased. The microhardness and compressive strength of the SLM W-2 wt% La 2 O 3 sample reached 455 HV and 2194 MPa, respectively. The toughness of the SLM W-2 wt% La 2 O 3 sample also improved significantly. One main reason was that the La 2 O 3 nanoparticles provide many heterogeneous nucleation sites to refine the grains. The other main reason was that La 2 O 3 nanoparticles formed into dislocation loops, which hindered the movement of dislocations and then increased the strength further. This research provided a new method to improve the mechanical properties of SLM W by introducing La 2 O 3 nanoparticles to achieve fine-grains strengthening and Orowan strengthening.