Formation evolution and strengthening of quasi-continuous network like TiB whiskers in the in-situ TiBw/TC21 matrix composites

Abstract

In-situ TiBw reinforced TC21 matrix composites with quasi continuous network structure were prepared by low energy ball milling and hot press sintering (HPS) in this work. The microstructure, mechanical properties and strengthening mechanism of TC21 matrix composites reinforced with different volume fraction of TiB were systematically studied. In-situ TiB whiskers with quasi-network structure can significantly refine the β Phase harmony α Phase size. It is also conducive to the formation of equiaxed α-Ti. The research shows that the strength of in-situ TiBw reinforced TC21 matrix composite is significantly better than that of the monolithic TC21 alloy. For example, the YS value and UTS value of in-situ TiBw/TC21 matrix composite containing 5.1 vol% are 1170 MPa and 1268 MPa respectively, which are 34.2% and 23.3% higher than those of the monolithic TC21 alloy under the same process conditions. This paper also analyzes the reason why the theoretical YS value of the composite material is greatly different from the experimental YS value, and believes that it may be that the TiB whisker forms a network structure, which affects the smooth transfer of load from the TiB whisker to the matrix.