Fabrication And Mechanical Properties Of Bulk Porous Amorphous

Bulk amorphous alloys have been used as biological materials due to their high strength, good wear and corrosion resistance. Compared with the natural bone of life agent, however, the high elastic modulus restricts the development of amorphous alloys. Therefore, the adoptions of bulk porous amorphous not only solve the problem of high elastics modulus, but also facilitate growing of bone cell in the pores. The porous Zr-based bulk metallic glass and the composite with lower elastic modulus was fabrication by melt infiltrating casting method. The morphologies, structures, fracture surfaces and phase constituent of the porous material and composite were investigaed by scanning electron microsscopy (SEM) and x-ray diffraction (XRD) respectively. The mechanical properties were obtained by compression tester. The the porosity was calculated by using the density obtained by Archimedes method. Furthermore, the hot processing window for metallic glasses was obtained by using specific tmpertaure. The results are as following:A uniform distribution of porous cells with size between 0.2 and 0.8 mm were formed by introducing CaC₂ particles as space holders. The density and porosity of the open-cellular bulk metallic glass are 3.63g/cm³ and 40.5% respectively. The maximal yield strength of the porous material is 384MPa followed by gradually-declining serrated flow stresses under compression. Final failure occurs at strains of 18.6%, well in excess of monolithic amorphous alloys.Then a 6 mm diameter composite with metallic glass matrix (Vit106) and Hydroxyapatite (HA), as second phase, was fabricated by using melt infiltration casting method. The results show that the HA particles are distributed uniformally in the amorphous matrix with good bonding interfaces with the matrix. The mechanical tests show that the compossive strength up to 250MPa and maximal elogation up to 65% were obtained for the as-cast samples. Compared with titanium-matrix composite with 20% vol HA used for as heavy load-bearing hard tissue replacement materials, the fracture strength for the amorphous matrix composite is much improved. The amorphous matrix HA composite also exhibits very high plastic deformation compared with porous bulk metallic glasses by considering the same strength level. It is suggested that the composite we investigated is preferred metal material for orthopaedics and implant biomaterials because of their high strength, good ductility and bio-compatibility.As to resolve the problem of comparing behaviours of isothermal stability of different alloy composites due to different relations between T_g and T_x, Through the digiter tools, the temperature- time data points can be selected among TTT diagrams for different amorphous alloys. Then the different serious of TTT diagrams are investigaed in the solitary themal window using the unification parameter formula. by analysis of constructing mathematics model, the linear slopes and intercepts presenting alloys are compared in order to ascertain thermal stable abilities of different amorphous, At the same time, enlarg the applications of amorphous in aspect of the thermal machining.