Guojian Hao

Reaction behaviors occurring in Ti/Al foil metallurgy

Reaction behaviors occurring in Ti/Al foil metallurgy were systematically investigated. Particular emphasis was focused on the reaction between solid Al and Ti as well as subsequent reaction between TiAl3 and Ti layer. In the solid reaction between Al and Ti, the presence of residual Al is mainly caused by inhomogeneous growth of TiAl3 layer and micro-voids existing at the interface. However, through reaction between molten Al and Ti, TiAl3/Ti multilayer can be achieved with complete consumption of Al. During subsequent high-temperature heat treatment, TiAl3/Ti multilayer will eventually turn into Ti3Al/TiAl multilayer accompanying with simultaneous formation and successive disappearance of intermediate phases, such as TiAl2 and Ti2Al5. Moreover, it is found that the growth direction of TiAl layer changes as a function of annealing time between different couples in multi-intermetallics system.

Tensile and compressive behavior of Ti-based bulk metallic glass composites

This article focuses on the tensile and compressive characteristics of a Ti-based bulk metallic glass composite (BMGC). It is found that the yield stress, maximum strength, and fracture strain are 1380 MPa, 1516 MPa, and 4.3% for uniaxial tension, but 1580 MPa, 4010 MPa, and 29% for uniaxial compression, respectively. The composite displays a linear “work hardening” capacity under compression; however, the “work softening” behavior is observed in the true engineering stress-strain curve upon tensile loading. The fracture surfaces of specimens also exhibit dissimilar properties under the different loadings.

Beryllium-distribution in metallic glass matrix composite containing beryllium

Abstract The morphologies, sizes, compositions and volume fractions of dendritic phases in in situ Ti-based metallic glass matrix composites (MGMCs) containing beryllium (Be) with the nominal composition of Ti 47 Zr 19 Cu 5 V 12 Be 17 (mole fraction, %) were investigated using XRD, SEM, EBSD, TEM, EDS and three-dimensional reconstruction method. Moreover, visualized at the nanoscale, Be distribution is confirmed to be only present in the matrix using scanning transmission electron microscopy–electron energy loss spectroscopy (STEM–EELS). Based on these findings, it has been obtained that the accurate chemical compositions are Ti 28.3 Zr 19.7 Cu 8 V 6.4 Be 37.6 (mole fraction, %) for glass matrix and Ti 62.4 Zr 18.4 Cu 2.6 V 16.6 (mole fraction, %) for the dendritic phases, and the volume fractions are 38.5% and 61.5%, respectively. It is believed that the results are of particular importance for the designing of Be-containing MGMCs.

Fracture Morphology and Local Deformation Characteristics in the Metallic Glass Matrix Composite Under Tension

Fracture and deformation characteristics of the Ti-based metallic glass matrix composite have been studied by the tensile test and the in situ TEM tension test. Typically, the composite exhibits the high strength and considerable plasticity. Microscopically, it was found that shear deformation zone formed at the crack tip in glass phase, which can bring about quick propagation of shear bands. However, the plastic deformation zone nearby the crack tip in dendrites will postpone or retard the crack extension by dislocations. The attributions of micro-deformations to mechanical properties of composites were discussed.