| In the paper, vacuum arc melting and water cooled copper crucible inductionskull melting had been used to prepare TiAl composites, and the Ti-48Al-B andTi-48Al-C composites were synthesized in situ. The microstructure of the TiAlcomposites had been analyzed through SEM, XRD, EDS and other experimentalmethods, the properties of the TiAl composites were tested through themicro-hardness, compression experiment, interface reaction, three-point bendingexperiment, the influence rule of B and C reinforced TiAl composites was obtained.Finally, the oxidation resistance of the Ti-48Al-1B and Ti-48Al-1C compositeswas studied after oxidized100h at800°C, and compared with the Ti-48Al binaryalloy.The Ti-48Al-x B and Ti-48Al-xC TiAl composites were fabricated by arcmelting, the experimental results showed that the Ti-48Al alloy was fully la mellarmicrostructure, and after adding B and C element, the microstructure of the TiAlcomposites was refined. With the increase of the element added, the reinforcedphase increased, and had a reunion phenomenon; the compression property of thecomposites was tested, with the increase of element added, the compressivestrength firstly increased and then decreased, the Ti-48Al-1B and Ti-48Al-1Ccomposites had maximum compressive strength, and the matrix o f compositematerials was brittle fracture though observing the fracture morphology. Throughanalyzing the interface reaction, the reaction layer thickness of Ti-48Al-x B andTi-48Al-xC composites decreased.It was found that the change of microstructure and properties of compositematerials which were fabricated by water cooled copper crucible induction me ltinghad a lot in common with those which were fabricated by arc melting. The Ti-48Alalloy organization was fully lame llar microstructure which consist of2(Ti3Al)and γ(TiAl) phase, the reinforced phases of Ti-48Al-B and Ti-48Al-C were TiB2and Ti2AlC separately, with the increase of the elements content, the reinforcedphases increased and their shape changed, TiB2phase changed from strip to block,Ti2AlC changed from strip to stick. The mechanical properties experimentsshowed that a balanced amount of reinforced phase could improve the performanceof the TiAl composites. Among them, with the increase of the ele ment content,themicro-hardness of Ti-48Al-B composites increased, that of Ti-48Al-C compositesfirstly increased and then decreased. The compressive strength and three-pointbending strength firstly increased and then decreased, when the B and C element content was1%, the strength was maximized.The oxidation experiments showed that after oxidated at800℃for100h, theweight ga in curve of the Ti-48Al-1B and Ti-48Al-1C composites went up moreslowly than that of the Ti-48Al binary alloy, the thickness of oxide layer decreased,and the Ti-48Al matrix peeled during oxidation process, the oxidation was serious.The Ti-48A-1B and Ti-48Al-1C composites improved oxidation resistanceproperties of the materials, but not much, especially Ti-48Al-1C contributed lessto the oxidation resistance properties of the composites. |
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