Abstract
To improve the strength and ductility of TiAl alloys by second phase,Ti46Al4Nb1Mo alloys doped with different B content(0.4％,0.8％,1.2％,1.6％and 2.0％,atomic percent,hereafter in at.％,referred to as TNM-xB)were prepared.Macro/microstructure evolution,mechanical properties and deformation mechanisms of the alloys were studied systematically.Results showed that the microstructure of TNM-0.4B and TNM-0.8B alloy remained columnar dendrites,and the secondary dendritic arms of columnar grains were more obvious.When the content of B is 1.2％,the columnar dendrites transformed to equiaxed grains,and theα2/γ lamellae colony size was further refined in TNM-1.6B and TNM-2.0B alloy.The morphologies and kinds of the borides were changed with increasing B content,XRD results showed that TiB phase ap-peared with 1.6％B content,and both TiB and TiB2 phase formed in TNM-2.0B alloy.There were straight and curved TiB phases located around grain boundaries in TNM-0.4B and TNM-0.8B alloy,and when the content of B increased to 1.2％,the curved TiB phases were reduced,while the tiny and straight TiB phases increased.With further increasing B content to 1.6％and 2.0％,the tiny and straight TiB phases were coarser.Compressive testing results showed that the mechanical properties of the TNM alloy were enhanced with increasing B content.The maximum strength and strain of TNM alloy were 2339MPa and 33.7％with 1.6％B addition.The compressive strength and strain were mainly enhanced via refinement of lamellar colony and formation of TiB,and it is found that pile-up of dislocations and deformed twins promoted by TiB are predominant in improving the mechanical properties of TNM alloys with higher strength and strain.
基金项目
National Natural Science Foun-dation of China(51825401)
National Natural Science Foun-dation of China(51971121)
China Postdoc-toral Science Foundation(2019TQ0077)
China Postdoc-toral Science Foundation(2019M660071)
NETL
NSTL
维普
万方数据