Effects of surface roughening on antibacterial and osteogenic properties of Ti-Cu alloys with different Cu contents

In order to reduce implant-related infections and improve early osseointegration,we performed HF+anodic oxidation on the surface of the new antibacterial Ti-Cu alloy to make the titanium-based implants have a micro/submicron structure.On this basis,a series of surface-modified Ti-x Cu alloys with different Cu contents(3,5 and 7 wt%)were fabricated and a comprehensive study was conducted on MC3 T3-E1 cell adhesion,proliferation,apoptosis and its antibacterial activity against Staphylococcus aureus.Results showed that the Ti-x Cu alloys by HF etching+anodized possessed multifunctional characteristics of antibiofilm and antibacterial abilities,excellent biocompatibility and osteogenesis promoting abilities.Increment of Cu content significantly contributed to the antibacterial and osteogenic properties of HF etching+anodized Ti-Cu alloys.Cell proliferation rates of HF etching+anodized Ti-7 Cu alloys were lower than those of Ti-3 Cu and Ti-5 Cu alloys,while the early cell apoptosis rates were higher than Ti-3 Cu and Ti-5 Cu groups.All the above results finally presented that the HF etching+anodized Ti-5 Cu alloy exhibited extremely strong antibacterial properties,good biological compatibility and osteogenic ability,as well as the most excellent ductility and corrosion resistance,providing a great potential application for the future dental implantation.

Influence of Cu addition on microstructure and hardness of near-eutectic Al-Si-xCu-alloys

The influence of Cu content on the microstructure and hardness of near-eutectic Al-Si-xCu（x = 2%,3%,4% and 5%） was investigated.After melting Al-based alloys with different Cu contents,alloys were cast in green sand molds at 690 °C and solidified.The solution treatment was performed at 500 °C for 7 h and then the specimens were cooled by water quenching.The samples were respectively aged at 190 °C for 5,10 and 15 h to observe the effect of aging time on the hardness of matrix.Also differential thermal analysis was used to obtain the transition temperature of the equilibrium phases at cooling rate of 30 K/min and to determine the effect of Cu content on the formation of quaternary eutectic phases and the melting point of-（Al） ＋ Si.The results show that as Cu content in the alloy increases,the hardness of matrix increases due to precipitation hardening,the melting point of -（Al） ＋ Si decreases and the amount of these eutectic phases increases,quaternary eutectic phase with melting point of 507 -C forms when Cu content is more than 2%.

Corrosion behaviors and mechanism of electroless Ni-Cu-P/n-TiN composite coating

In the present investigation, electroless Ni-Cu-P/n-TiN composite coating was prepared using alkaline citrate-based bath. X-ray diffraction （XRD）, scanning electron microscopy（SEM）, energy-dispersive spectroscopy（EDS）, electrochemical measurements, weight loss tests and Raman spectrometer were used to character the properties of the coating. As the Cu content increased from 7.3 wt% to 24.8 wt%, the corrosion current density of the Ni-Cu-P/n-TiN coating decreased from 10.80 to 4.34 ~tA. And the inclusion of Cu in NiP alloy resulted in refinement and less porosity in microstructure. The addition of TiN resulted in a slight decline in anti-corrosion property of the coating. As the mass loss test showed, Ni-24.8%Cu-P exhibited perfect corrosion resistance. Studies by Raman spectroscopy on coatings proved that Cu（II）3（PO4）（OH）3, Cu（OH）2 and CuO were examined while no compound of nickel was found, and Cu exhibited preferred corrosion in saline solution, providing cathodic protection to Ni alloy.

Influence of Cu content on microstructure and mechanical properties of thixoformed Al-Si-Cu-Mg alloys

The effects of Cu content on the microstructure and mechanical properties of thixoformed Al-6Si-xCu-0.3Mg(x= 3,4,5and 6,mass fraction,%) alloys were studied.The samples were thixoformed at 50%liquid content and several of the samples were treated with the T6 heat treatment.The samples were then examined by optical microscopy(OM),scanning electron microscopy(SEM),energy dispersive X-ray(EDX) spectroscopy and X-ray diffraction(XRD) analysis,as well as hardness and tensile tests.The results show that the cooling slope casting and thixoforming process promote the formation of very fine and well distributed intermetallic compounds in the aluminium matrix and the mechanical properties of the alloys increase considerably compared with the permanent mould casting.The results also reveal that as the Cu content in the alloy increases,the hardness and tensile strength of the thixoformed alloys also increase.The ultimate tensile strength,yield strength and elongation to fracture of the thixoformed heat-treated Al-6Si-3Cu-0.3Mg alloy are 298 MPa,201 MPa and 4.5%,respectively,whereas the values of the thixoformed heat-treated alloy with high Cu content(6%) are 361 MPa,274 MPa and 1.1%,respectively.The fracture of the thixoformed Al-6Si-3Cu-0.3Mg alloy shows a dimple rupture,whereas in the alloy that contains the highest Cu content(6%),a cleavage fracture is observed.

Self-propagating High-temperature Synthesis, Microstructure and Mechanical Properties of TiC-TiB_2-Cu Composites

TiC-TiB2-Cu composites were produced by self-propagating high-temperature synthesis combined with pseudo hot isostatic pressing using Ti, B4C and Cu powders. The microstructure and mechanical properties of the composites were investigated. The X-ray diffraction （XRD） and scanning electron microscopy （SEM） results showed that the final products were only TiC, TiB2 and Cu phases. The clubbed TiB2 grains and spheroidal or irregular TiC grains were found in the microstructure of synthesized products. The reaction temperature and grain size of TiB2 and TiC particles decreased with increasing Cu content. The introduction of Cu into the composites resulted in a drastic increase in the relative density and flexual strength, and the maximum values were obtained with the addition of 20 wt pct, while the fracture toughness was the best when Cu content was 40 wt pct.

Effects of Cu content on microstructure and mechanical properties of rheo-diecasting Al-6Zn-2Mg-xCu alloys

A systematic study on how Cu content affects the microstructure and mechanical properties of rheo-diecasting Al-6Zn-2Mg-xCu alloys during solution treatment and ageing heat treatment was conducted.The swirled enthalpy equilibrium device(SEED)was adopted to prepare the semi-solid slurry of Al-6Zn-2Mg-xCu alloys.The microstructure development and mechanical properties were studied using optical microscopy(OM),scanning electron microscopy(SEM),X-ray diffraction(XRD),differential scanning calorimetry(DSC),as well as hardness and tensile testing.The grain boundary and shape factor were calculated using image processing software(Image-Pro Plus 6.0).Results show that the alloys are composed of typical globular primaryα-Al grains,eutectic phases,and smaller secondaryα-Al grains.After solution and ageing heat treatment,the eutectic phases are dissolved into Al matrix when the Cu content is lower than 1.5wt.%,while some eutectic phases transform into Al_(2)CuMg(S)phases and remain at grain boundaries when Cu content reaches 2wt.%.T6 heat treatment significantly enhances the mechanical properties of rheo-diecasting Al-6Zn-2Mg-xCu alloys.When Cu concentration is 0.5wt.%-1.5wt.%,the ultimate tensile strength,yield strength and elongation of T6 treated alloys rise to around 500 MPa,420 MPa,and 18%,respectively.

Effect of Cu Content on Aging Precipitation Behaviors of Cu-Rich Phase in Fe-Cr-Ni Alloy

The precipitation characteristics and effect on strengthening mechanism of Cu-rich phases during short-time and long-time aging for Super 304H steels with different Cu content were investigated using X-ray diffraction （XRD）, scanning electron microscope （SEM） and transmission electron microscope （TEM）. The results show that the size of Cu-rich phase particles increases, the interspace of Cu-rich phase particles decreases and the density of Curich phases increases with the increase of Cu content during short-time aging （approximately 800 h） at 650℃ for Super 304H steels. During long-time aging （more than 2 000 h） at 650 ℃, Cu-rich phase precipitates sufficiently and the strengthening effect of Cu-rich phase is preferable in Super 304H steel containing Cu of 4%. The strengthening effect of Cu-rich phase in Super 304H steels containing Cu of 2.2% or 5% is weaker than that with Cu of 4% during long-time aging （more than 2 000 h）.

Microstructure and magnetic properties of Fe81.3Si4B13Cu1.7 nanocrystalline alloys with minor Nb addition

The amorphous matrix contAlning dispersive high number density （Na） α-Fe nuclei with average grAln sizes （D） of 4.3-6.2 nm was formed in the melt-spun Fe81.3-xSi4B13Cu1.7Nbx （x = 0-2） alloys, and the Nd and D values reduce with increase in the Nb content. The fine nanocrystalline structure with α-Fe grAlns of 14.0-21.6 nm in size was obtAlned for the annealed alloys, which showed high saturation magnetic flux density of 1.60-1.77 T and low coercivity （He） of 7.1-17.0 A/m. Addition of minor Nb significantly expands the optimum annealing temperature range for obtAlning good soft magnetic properties, while coarsens the α-Fe grAlns, leading to a slight increase in the Hc. The mechanism of the effect of Cu and Nb elements on the structure and magnetic properties was discussed in terms of the formation and growth of the α-Fe nuclei of the alloys.