TiC/TiAl composites with different TiC content were fabricated by rapid heating technique of spark plasma sintering (SPS). The effect of TiC particles on microstructure and mechanical properties of TiAl Matrix was inv...TiC/TiAl composites with different TiC content were fabricated by rapid heating technique of spark plasma sintering (SPS). The effect of TiC particles on microstructure and mechanical properties of TiAl Matrix was investigated. The results indicate that grain sizes of TiAl matrix decrease and mechanical properties are improved because of the addition of TiC particles. The composites display a 26.8% increase in bending strength when 10 wt% TiC is added and 43.8% improvement in fracture toughness when 5 wt% TiC is added compared to values of TiC-free materials. Grain-refinement and dispersion-strengthening were the main strengthening mechanism. The improvement of fracture toughness was due to the deflexion of TiC particles to the crack.展开更多
The performance of Al-Ti-C master alloy in refining Al-10Mg and Al-5Cu alloys was studied by using electron probe micro-analyzer （EPMA） and X-ray diffractometer （XRD） analysis. The results indicate that there are ...The performance of Al-Ti-C master alloy in refining Al-10Mg and Al-5Cu alloys was studied by using electron probe micro-analyzer （EPMA） and X-ray diffractometer （XRD） analysis. The results indicate that there are obvious fading phenomena in both Al-10Mg and Al-5Cu alloys with the addition of Al-5Ti-0.4C refiner which contains TiC and TiAl3 compounds. Mg element has no influence on the stability of TiC and TiAl3, while TiC particles in Al-10Mg alloy react with Al to form Al4C3 particles, resulting in the refinement fading. However, TiC particles are relatively stable in Al-5Cu alloy, while TiAl3 phase reacts with Al2Cu to produce a new phase Ti（Al, Cu）2, which is responsible for the refinement fading in Al-5Cu alloy. These indicate that the refinement fading will not occur only when both the TiC particles and TiAl3 compound of Al-Ti-C refiner are stable in Al alloys.展开更多
TiAl alloys were joined to TiC cermets using combustion synthesis method. The Ti-C-Ni metallic powder compact acted as a joining interlayer in the joining process. The identification and mechanisms of the reaction at ...TiAl alloys were joined to TiC cermets using combustion synthesis method. The Ti-C-Ni metallic powder compact acted as a joining interlayer in the joining process. The identification and mechanisms of the reaction at the interface and interlayer were investigated. From the analysis of the microstructure of TiAl/TiC cermet joint, it is noted that TiC and TiNi compounds are main reaction products and unreacted Ni is observed in the interlayer. The reaction products consist of a large volume of voids or unreacted regions. It is confirmed that Al addition as well as joining pressure are effective to decrease the voids. It is considered that high flowability of liquid Al enhances the SHS reaction and the densification of reaction products. There is a continuous Ni-rich layer observed at the interface between the interlayer and TiC cermets substrate. Ti3Al, TiC and TiNi compounds are observed in the reaction products.展开更多
Using spark plasma sintering（SPS） technique, TiC particle reinforced γ-TiAl composites were prepared with varying weight fraction of TiC powders. The effects of the TiC fractions and distributions on the properties...Using spark plasma sintering（SPS） technique, TiC particle reinforced γ-TiAl composites were prepared with varying weight fraction of TiC powders. The effects of the TiC fractions and distributions on the properties of the composites were investigated. The composite containing 7wt% TiC had the optimum three-point bending strength of 842 MPa,which was 200 MPa greater than that of the unreinforced γ-TiAl intermetallic. The degradation of the bending strength occurred in the composites containing more than 7wt% TiC and this was believed to be attributed to agglomerated particles of TiC, which acted as crack initiation and propagation sites. The increase of strength in TiC reinforced IMCs came from the grain refinement and the interaction of dislocations with the reinforcing particles. The bending strength of the IMC containing 7wt% TiC was theoretically estimated to increase by 85 MPa and 200 MPa, respectively, by the grain refinement and dislocation strengthening, the total of which was ahnost in accordance with the improvement in that of the unreinforced γ-TiAl intermetallic when considering normal estimation errors.展开更多
文摘TiC/TiAl composites with different TiC content were fabricated by rapid heating technique of spark plasma sintering (SPS). The effect of TiC particles on microstructure and mechanical properties of TiAl Matrix was investigated. The results indicate that grain sizes of TiAl matrix decrease and mechanical properties are improved because of the addition of TiC particles. The composites display a 26.8% increase in bending strength when 10 wt% TiC is added and 43.8% improvement in fracture toughness when 5 wt% TiC is added compared to values of TiC-free materials. Grain-refinement and dispersion-strengthening were the main strengthening mechanism. The improvement of fracture toughness was due to the deflexion of TiC particles to the crack.
基金This work was financially supported by the National Natural Science Foundation of China (No.50171037).
文摘The performance of Al-Ti-C master alloy in refining Al-10Mg and Al-5Cu alloys was studied by using electron probe micro-analyzer （EPMA） and X-ray diffractometer （XRD） analysis. The results indicate that there are obvious fading phenomena in both Al-10Mg and Al-5Cu alloys with the addition of Al-5Ti-0.4C refiner which contains TiC and TiAl3 compounds. Mg element has no influence on the stability of TiC and TiAl3, while TiC particles in Al-10Mg alloy react with Al to form Al4C3 particles, resulting in the refinement fading. However, TiC particles are relatively stable in Al-5Cu alloy, while TiAl3 phase reacts with Al2Cu to produce a new phase Ti（Al, Cu）2, which is responsible for the refinement fading in Al-5Cu alloy. These indicate that the refinement fading will not occur only when both the TiC particles and TiAl3 compound of Al-Ti-C refiner are stable in Al alloys.
文摘TiAl alloys were joined to TiC cermets using combustion synthesis method. The Ti-C-Ni metallic powder compact acted as a joining interlayer in the joining process. The identification and mechanisms of the reaction at the interface and interlayer were investigated. From the analysis of the microstructure of TiAl/TiC cermet joint, it is noted that TiC and TiNi compounds are main reaction products and unreacted Ni is observed in the interlayer. The reaction products consist of a large volume of voids or unreacted regions. It is confirmed that Al addition as well as joining pressure are effective to decrease the voids. It is considered that high flowability of liquid Al enhances the SHS reaction and the densification of reaction products. There is a continuous Ni-rich layer observed at the interface between the interlayer and TiC cermets substrate. Ti3Al, TiC and TiNi compounds are observed in the reaction products.
基金the Natural Science Foundation of Shandong Province(No.Z2003F02)
文摘Using spark plasma sintering（SPS） technique, TiC particle reinforced γ-TiAl composites were prepared with varying weight fraction of TiC powders. The effects of the TiC fractions and distributions on the properties of the composites were investigated. The composite containing 7wt% TiC had the optimum three-point bending strength of 842 MPa,which was 200 MPa greater than that of the unreinforced γ-TiAl intermetallic. The degradation of the bending strength occurred in the composites containing more than 7wt% TiC and this was believed to be attributed to agglomerated particles of TiC, which acted as crack initiation and propagation sites. The increase of strength in TiC reinforced IMCs came from the grain refinement and the interaction of dislocations with the reinforcing particles. The bending strength of the IMC containing 7wt% TiC was theoretically estimated to increase by 85 MPa and 200 MPa, respectively, by the grain refinement and dislocation strengthening, the total of which was ahnost in accordance with the improvement in that of the unreinforced γ-TiAl intermetallic when considering normal estimation errors.
