Abstract: The KC and DBTT of both sintered and recrystallized Mo alloy doped with La2O3 (Mo- La2O3) as well as unalloyed molybdenum were tested and the microstructure was investigated by SEM, TEM and AES. The results show that the KC of Mo- La2O3 alloy reaches to 24.76MPa·m1/2, which is 2.5 times as much as that unalloyed Mo. The DBTT of Mo- La2O3 sheet annealed at 1900℃ for 60min is decreased to -60℃, which is 80℃ lower than that of unalloyed Mo. The Mo- La2O3 alloy has similar equiaxed grain structure with the unalloyed Mo. The AES analysis revealed that the same content of interstitial impurities exist on grain boundaries of Mo- La2O3 and unalloyed Mo. A toughening mechanism was proposed to be that large number of dislocations were pinned around La2O3 particles, shorting the efficient slip length and decreasing the dislocations pile-up on grain boundaries of Mo. The toughness improvement of Mo- La2O3 alloy was attributed to the relax of stress concentration at grain boundaries of Mo- La2O3 alloy and the weaker tendency to intergranular fracture on grain boundaries.
The KⅠC and DBTT of both sintered and recrystallized Mo alloy doped with La2O3(Mo-La2O3) as well as unalloyed molybdenum were tested and the microstructure was investigated by SEM, TEM and AES. The results show that the KⅠC of Mo-La2O3 alloy reaches to 24.76MPa·m1/2, which is 2.5 times as much as that unalloyed Mo. The DBTT of Mo-La2O3 sheet annealed at 1900℃ for 60 min is decreased to -60℃, which is 80℃ lower than that of unalloyed Mo. The Mo-La2O3 alloy has similar equiaxed grain structure with the unalloyed Mo. The AES analysis revealed that the same content of interstitial impurities exist on grain boundaries of Mo-La2O3 and unalloyed Mo. A toughening mechanism was proposed to be that large number of dislocations were pinned around La2O3 particles, shorting the efficient slip length and decreasing the dislocations pile-up on grain boundaries of Mo. The toughness improvement of Mo-La2O3 alloy was attributed to the relax of stress concentration at grain boundaries of Mo-La2O3 alloy and the weaker tendency to intergranular fracture on grain boundaries.