Boosted mechanical properties of sintered MoLa alloys with ultrafine-grains by the nanostructuring of secondary phase

The secondary phase particles of La 2 O 3 play a crucial role in the determination of the yield strength over MoLa alloys, but few work focuses on their intrinsic modulation of shape and size. Herein, a nanostructuring strategy of the secondary phase particles is proposed to enhance the mechanical performances of MoLa alloys, in which the shape and size effects of secondary phase particles have been discussed. Moreover, the strengthening mechanism is also analyzed. It is found that the La 2 O 3 nanospheres with a small size of 84 nm exhibit the best strengthening ability, leading to a high yield strength of 765 MPa in the sintered state. Smaller particles are easily involved into the Mo matrix interior to be intragranular, which are beneficial for the further strengthening. The strengthening contributions are quantitatively calculated, providing a predicted yield strength value, which is in good agreement with the measured one.