Nano Mo-La-O particles strengthened Mo alloys fabricated via freeze-drying technology and low temperature sintering

This work proposed an innovative technology to fabricate Mo-La-O nanoparticles strengthened Mo alloys with ultrafine nano grains via freeze-drying and low temperature sintering. These novel nano Mo-La-O particles including La7Mo7O30, La5Mo3O16, La6Mo2O15, La5Mo4O12, La4Mo2O11 and La-2(MoO6) remain coherent or semi-coherent interfaces with Mo matrix to strengthen their phase boundaries. Moreover, nano Mo-La-O particles enriched in excess oxygen absorb nearby impurity oxygen and then lead to the purification of Mo matrix. Furthermore, the low temperature sintered Mo-LaxMoyOz alloys possess high relative density (98.1%), which is due to the high sintering activities of ultrafine powders (56 nm). Comparing with available literature which involves oxide-dispersion-strengthened-molybdenum alloys (ODS-Mo), the freeze-dried Mo-LaxMoyOz alloys in our work possess the finest grain size (440 nm), the finest oxide particle size (mainly <5 nm), the highest hardness (495 HV0.2) and high strength (1201 MPa) at 30% deformation.

Automated summary

This study introduces an innovative technology to fabricate Mo-La-O nanoparticles strengthened Mo alloys with high density, fine grain and high strength through freeze-drying and low temperature sintering.