Effect Of WC And SiC On The Microstructure And Mechanical Properties Of TiAl Binary Alloys

TiAl based alloys have many excellent integrated mechanical properties and are widely applied in space and automotive applications.With the development of aerospace engines towards faster and stronger goals,As structural materials the mechanical properties of TiAl alloys need to be further improved.Alloying is an useful method and intermetallic matrix composite technology is an other way to improve the comprehensive mechanical properties of alloys.In this paper,WC and SiC were put into TiA1 binary alloys by vacuum arc melting furnace.The different mass fraction of WC and SiC would react with Ti、Al in high melting temperature.The influence of new reinforcements and alloying to the microstructure of Ti43 Al and Ti47 Al was studied by OM、SEM、EPMA、XRD and other test methods.The room temperature compression performance were tested to figure out the changing trend under the increasing content of WC and SiC.Finally,the effect mechanism and strengthening mechanism of WC and SiC was discussed.The experimental results show that when the WC is put into the Ti43 Al alloys,the microstructure of the Ti43Al-xWC has been refined.At the same time,the compressive strength and compressive strain have been improved.The Ti43Al-4.5wt%WC has the smallest spacing of its branches and the highest compressive strength is 1235.11 MPa,which is 46.62% higher than the Ti43 Al based alloy.When the contentof WC is 6.0wt% and 7.5wt%,Slender needle-like reinforcements appear in the alloy matix and the XRD analysis shows that the reinforcements are Ti2 AlC.Its room temperature compression properties decreases at the same time.WC has a significant impact on the microstructure and mechanical properties of Ti47 Al.With the increasing addition of WC,more and more rod-like particles appear in the matrix and the distribution is fairly uniform.The XRD analysis shows that Ti2 AlC reinforcements are generated in the matrix and the strongest diffraction peak of α2 is shifted to the left.The microstructure of Ti47Al-xWC is obviously refined,which changes from columnar into equiaxial grain.The grain size is reduced from 141.86 μm to 60.02μm and the room temperature compressive strength and compressive stain are gradually enhanced.The Ti47Al-6.0wt%WC has the highest compressive strength,which is 2323.99 MPa and is about 21.19% higher than the based alloys.When the addition content of SiC is 0.1,0.3,0.5,and 0.7wt %,the changes of microstructureand mechanical properties are not obvious.But when the addition content of SiC reaches 0.9wt%,the grain size is 105.99μm.The microstructure is significantly refined and changes into equiaxial grain.The compression strength is greatly improved,which reaches 1382.72 MPa and is 64.14% higher than the based alloys.SiC has a significant impact on the microstructure and mechanical properties of Ti47 Al.With the increasing content of SiC,more and more rod-like Ti2 AlC appear in the matrix and lots of silicide precipitatesdistribute in the grain boundary.When the addition content of SiC is 0.5wt%,the highest compressive strength is 2196.49 MPa,which is 19.94% higher than the based alloys.