摘要
To better understand the strengthening mechanism of in-situ formed TiB reinforcements in dual-phase Ti6 Al4 V alloy,the interface characters and properties ofα-Ti/β-Ti/TiB system were thoroughly investigated with the combined use of high-resolution transmission electron microscopy(HRTEM),abinitio calculations,and indentation tests.The ab-initio calculations suggest that the highly coherent(100)_(TiB)/(121)_(β-Ti)phase boundary(PB)has fairly low interface energy of 0.082 J/m^(2)with an exceptionally high adhesion strength of 6.04 J/m^(2),owing to the formation of strong interfacial Ti–B ionic bonds.The semi-coherent(201)_(TiB)/(0001)_(α-Ti)interface shows a relatively higher interface energy of 1.442 J/m^(2)but still with a fairly high adhesion strength of 4.95 J/m^(2).With the obtained interfacial energetics,thermodynamics analyses were further carried out to explore the nucleation mechanism ofα-Ti in TiB reinforced Ti6Al4V composite.Superior to the heterogeneous nucleation at TiB/β-Ti interface,the homogeneous nucleation ofα-Ti within theβ-Ti phase can be more energy-preferred,due to its lower nucleation energy barrier and critical radius.Further indentation tests under various loads of different modes confirmed a remarkably enhanced load-bearing capacity of dual-phase Ti6Al4V alloys,under the critical significance of the strong interfacial bonding achieved by reinforcements of in-situ formed TiB.
基金
financially supported by National Key R&D Program of China(No.2021YFB3701203)
the National Natural Science Foundation of China(NSFC)under the Grant Nos.52171137,51731009,and 52071116
Heilongjiang Postdoctoral Fund(No.LBHZ20058)
Heilongjiang Provincial Natural Science Foundation of China(No.TD2020E001)
Key-Area Research and Development Program of Guang Dong Province(No.2019B010942001)。
