Mechanical Properties and Microstructure of Nb/Nb5Si3/Cr2Nb Alloys Prepared by Spark Plasma Sintering

摘要

Through the spark plasma sintering technology (SPS), the Nb/Nb_5Si_3/Cr_2Nb mixed powders with different volume ratios of 7:1:2 and 7:2:1 were sintered into ingots. The effects of three powder mixing methods on phase constitution, microstructure and room-temperature mechanical properties of the ternary Nb/Nb_5Si_3/Cr_2Nb alloys were investigated. The result shows that the method of dry mixing without ball milling is advantageous for toughness, the increase of SPS temperature decreases the toughness whereas improves the hardness. The stiffening Nb_5Si_3 and Cr_2Nb phases tend to form a continuous network, resulting in decrease of toughness. It is interesting that when the fractions of the Nb_5Si_3 phase larger than that of the Cr_2Nb phases, these strengthening phases prefer to appear in the form of network, which is detrimental for toughness.