Abstract:
The Nb-NbCr
2 alloy with 0.5at.% B
4C was prepared by mechanical alloying and hot pressing. To investigate the effects of B
4C on thermal stability of Nb-NbCr
2 alloy, the samples were thermally exposed at 1 200℃ for 30~100 h in vacuum, respectively. The results show that composition phases of B
4C/Nb-NbCr
2 alloy have no obvious change after the thermal exposure process. The relative density of B
4C/Nb-NbCr
2 alloy increases from 98.6% to 98.7% and the change is significantly smaller than Nb-NbCr
2 alloy without B
4C addition. Laves phase NbCr
2 particles of B
4C/Nb-NbCr
2 alloy have a little aggregation and growth after the thermal exposure process, but the phenomenon of aggregation and growth of Laves phase NbCr
2 particles is much less than Nb-NbCr
2 alloy without B
4C addition. After thermal exposure for 50 h, the Vickers hardness of B
4C/Nb-NbCr
2 decreases by 10.1% after the first 50 h and decreases by only 1.7% after the later 50 h, and the change is significantly smaller than Nb-NbCr
2 alloy without B
4C addition. After thermal exposure for 100 h, the compressive strength and plastic strain of B
4C/Nb-NbCr
2 alloy change from 3 048 MPa and 12.7% to 2 788 MPa and 20.7%, respectively, and the change is significantly smaller than Nb-NbCr
2 alloy without B
4C addition. In general, it can be seen that the B
4C particles can improve the thermal stability of Nb-NbCr
2 alloy.