The Ti Bw reinforced near-α titanium matrix composite（Ti-5.8 Al-3.4 Zr-4.0 Sn-0.4 Mo-0.4 Nb-0.4 Si-0.06 C） was successfully synthesized by powder metallurgy and hot extrusion route. The effects of solution and aging temperature on the microstructure and high temperature tensile properties of the composite were investigated. The results revealed that the fine transformed β phase can be obtained by the solution treatment at β phase region and aging treatment, no other precipitates were observed. The α2 phase（Ti3 Al） can be acquired when the solution treated at α＋β phase region followed by aging treatment. With increasing the aging temperature from 500 to 700℃ for 5 h, the size of α2 precipitates increases from about 5 to about 30 nm. The Ti Bw are stable without any interfacial reaction during the heat treatments. The high temperature tensile properties show that the composite performed by solution and aging treatment exhibits good strengthening effects. With increasing the aging temperature from 500 to 700℃, the strength of the composite increases at the expense of elongation due to the increment of α2 precipitates.The strength of the composite at 600℃ increases by 17% to 986 MPa after 1000℃/2 h/AC and 700℃/5 h/AC heat treatment.
WANG BoZHANG HaoBiaoHUANG LuJunHE JianLiZHANG YouFengWANG Wei
YSZ/（Ni, Al） composite coatings were deposited on Inconel600 superalloy with ball peening （BP） and without （non BP）treatment using the electrophoretic deposition （EPD） technique, followed by vacuum sintering method. The structures and phaseevolution of the coatings were studied with X-ray diffraction （XRD）, scanning electron microscopy （SEM） and energy dispersivespectrometry （EDS）. The relation between microstructures and properties of the BPs-coated samples was discussed. The results showthat the adhesion strength and gain mass of the BPs-coated samples with isothermal oxidation at 1100℃ for 100 h are 3.3 N and0.00817 mg/cm^2, respectively, while those of the non-BPs-coated sample are 2.6 N and 0.00559 mg/cm^2, respectively. The EDSmapping analysis indicates that an obvious outward diffusion of Cr from the substrate to BPs coated samples occurs after isothermaloxidation. The BPs-coated sample shows the superior adhesion and oxidation resistance compared with non-BPs-coated samples.
Yttria-stablized zirconia(YSZ)/(Ni,Al)coatings were deposited on Inconel600alloy substrate by the electrophoreticdeposition combined with vacuum sintering technique.The effects of isothermal oxidation at1100°C on the composition of thecoatings and the crack healing were investigated,and the corrosion resistance of the coatings in3.5%NaCl(mass fraction)solutionwas also studied.The results showed that the cracks on the coating gradually healed up with the increase of the isothermal oxidationtime.During isothermal oxidation process,the coating composed of Ni3Al was transformed toα-Al2O3particulates.Theα-Al2O3particulates can seal the defects such as pores and cracks,and meanwhile prevent the oxygen diffusion into the coatings.Thepolarization curves and EIS results indicated that the coatings oxidized for40h had a more positive corrosion potential,higherbreakdown potential,higher impedance module at low frequency and much lower corrosion current density compared with YSZcoated and uncoated Inconel600alloys.
