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The effects of Zn,P and Mg additions on the microstructure and mechanical properties of Nb-22Ti-3Si alloys were studied. The phases of Nbss and Nb_3Si presented in Nb-22Ti-3Si(AC1),Nb-22Ti-3Si-0.2Zn(AC2) and Nb-22Ti-3Si-0.2Mg alloys(AC3). The Nb-22Ti-3Si-0.2P(AC4) alloy consisted of Nbss,Nb_3Si network and eutectic cell of Nbss/α-Nb_5Si_3.By the addition of Zn,the Nb_3Si network was broken and the volume fraction of Nbss increased from 92%to 96%.The values of fracture toughness of the alloy AC2 at ambient temperature increased from 22,58 MPa·m~(1/2) to 26.41 MPa·m~(1/2).The values of compressive strength for the Zn-added alloy at ambient temperature and 1 250℃increased from 1 525.10 MPa to 1 652.44 MPa,and from 268.52 MPa to 284.18 MPa,respectively.Compared with the alloy AC1,the addition of P promoted the formation ofα-Nb_5Si phase but the values of fracture toughness and compressive strength of alloy at room temperature and 1 250℃decreased.In contrast,the addition of Mg improved the compressive strength at ambient temperature and 1250℃from 1 525.10 MPa to 1 618.08 MPa and from 268.52 MPa to 348.28 MPa,respectively.The relationship between the microstructure and the mechanical properties was discussed.
The effects of Zn, P and Mg additions on the microstructure and mechanical properties of Nb-22Ti-3Si alloys were studied. The phases of Nbss and Nb_3Si presented in Nb-22Ti-3Si (AC1), Nb-22Ti-3Si-0.2Zn (AC2) and Nb-22Ti-3Si-0.2Mg alloys (AC3). The Nb-22Ti-3Si-0.2P (AC4) alloy consisted of Nbss, Nb_3Si network and eutectic cell of Nbss / α-Nb_5Si_3.By the addition of Zn, the Nb_3Si network was broken and the volume fraction of Nbss increased from 92% to 96%. The values of fracture toughness of the alloy AC2 at ambient temperature increased from 22,58 MPa · m ~ (1/2) to 26.41 MPa · M ~ (1/2). The values of compressive strength for the Zn-added alloy at ambient temperature and 1 250 ℃ increased from 1 525.10 MPa to 1 652.44 MPa, and from 268.52 MPa to 284.18 MPa, respectively. Compared with the alloy AC1, the addition of P promoted the formation of α-Nb_5Si phase but the values of fracture toughness and compressive strength of alloy at room temperature and 1 250 ℃ decreased.In contrast, the addition of Mg impro ved the compressive strength at ambient temperature and 1250 ° C from 1 525.10 MPa to 1 618.08 MPa and from 268.52 MPa to 348.28 MPa respectively.The relationship between the microstructure and the mechanical properties was discussed.