Preparation of hydroxyapatite layer on Ti-based bulk metallic glasses by acid and alkali pre-treatment

In this paper, a thin calcium phosphate layer was prepared on the surface of Ti4oZr10Cu36Pd14 bulk metallic glasses （BMGs）. All samples were dipped in HNO3 aqueous solution and boiled in 1.2 mol-L-I NaOH aqueous solution. After the two preliminary treatment steps, they were soaked in simulated body fluid （SBF） to form an apatite layer on the surface. After immersion for 12 days, a coating composed mainly of Ca-P particles was rapidly deposited on the surface of Ti40Zr10Cu36Pd14 bulk metallic glasses. The surfaces of chemically treated sam- ples and the samples after immersion in SBF were char- acterized by X-ray diffraction （XRD）, X-ray photoemission spectroscopy （XPS）, field emission scanning electron microscopy （FESEM）, and energy dispersive spectroscopy （EDS）. Analysis results indicate that this apatite coating consists of Ca-P particles with different diameters. In addition, the Ca/P ratio of the apatite coatings immersed for 14 days is 1.62, which is close to that of hydroxyapatite （HA）.

Microstructure and mechanical properties of TC4 joints brazed with Ti-Zr-Cu-Sn amorphous filler alloy

The Ti_(51.44)Zr_(16.26)Cu_(30)Sn_(2.3)(at%)amorphous filler alloy in a ribbon form was prepared by melt spinning.The Ti-6 Al-4 V alloy was brazed in vacuum furnace by using the Ti_(51.44)Zr_(16.26)Cu_(30)Sn_(2.3)amorphous filler alloy.The effects of brazing temperature and holding time on the interfacial microstructure and mechanical properties of the Ti-6 Al-4 V brazed joints were investigated.The brazed joints are composed ofα-Ti,β-Ti,and(Ti,Zr)_(2)Cu phases.The shear strength of the joints increases with brazing temperature increasing from 1153 to 1193 K and holding time from 10 to 15 min,while decreases with brazing temperature and time further increasing.Low temperature brazing results in the formation of microcracks and voids in the seams,which are harmful for the shear strength of the joints.In the joint brazed at 1193 K for 15 min,a fineα+βWidmansta¨tten structure beneficial to the mechanical property is formed,and the joint exhibits relatively high joint strength of 180 MPa.

Zr_(55)Al_(10)Ni_(5)Cu_(30)amorphous alloy film prepared by magnetron sputtering method

In this work,amorphous Zr_(55)Al_(10)Ni_(5)Cu_(30)alloy thin film was prepared on D36 steel substrate by magnetron sputtering method.The film was characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),atomic force microscopy(AFM),hardness tester and nano indentation.Corrosion behavior of the film was investigated in 3.5%NaCl aqueous solutions by an electrochemical method.At room temperature,the amorphous alloy film was formed completely after sputtering for 5 h.The surface morphology of the amorphous alloy film was uniform and smooth.Formation of the amorphous alloy film improved the microhardness and corrosion resistance of the D36 substrate.The amorphous alloy film(prepared at room temperature for 5 h)exhibited good adhesion strength with the substrate.The as-sputtered sample exhibited a crevice corrosion trend when the sputtering time was too short(1 h)or too long(10 h).