Microstructure and properties of Al-doped ODS steels prepared by wet-milling and SPS methods

In this paper,15Cr-ODS steels containing 0,1 wt%,2 wt%and 3 wt%Al element were fabricated by combining wet-milling and spark plasma sintering(SPS)methods.The microstructure and mechanical properties of ODS steel were investigated by XRD,SEM,TEM,EBSD and tensile tests.The results demonstrate that the Al addition significantly refines the particle precipitates in the Fe-Cr matrix,leading to the obvious refinement in grain size of matrix and the improvement of mechanical properties.The dispersion particles in ODS steels with Al addition are identified as Al2O3 and Y_(2)Ti_(2)O_(7)nanoparticles,which has a heterogeneous size distribution in the range of 5 nm to 300 nm.Increasing Al addition causes an obvious increase in tensile strength and a decline in elongation.The tensile strength and elongation of 15Cr-ODS steel containing 3 wt%Al are 775.3 MPa and 15.1%,respectively.The existence of Al element improves the corrosion resistance of materials.The ODS steel containing 2 wt%Al shows corrosion potential of 0.39 V and passivation current density of 2.61×10^(−3)A/cm^(2)(1.37 V).This work shows that Al-doped ODS steels prepared by wet-milling and SPS methods have a potential application in structural parts for nuclear system.

Effects of femtosecond laser micropatterning on the surface properties and cellular response of biomedical tantalum-blended composites

Poly(ε-caprolactone)(PCL)holds unique bioresorbability and competent biomechanical properties for tissueengineering application.However,PCL is hydrophobic intrinsically and poor in cell-biomaterial interaction.In this study,we prepared a composite based on PCL and bioactive tantalum(Ta)to understand the effects of direct laser micropatterning on composite surface properties.The PCL/Ta composite after preparation was surface-patterned by femtosecond laser and characterized with surface morphology,crystal structure,chemical composition,wettability and cellular response of fibroblast.It was found that laser micropatterning enlarged the difference of wetting properties(~15°)on PCL and PCL/Ta surfaces.The wetting changes was dependent on both material composition and lasermachined geometry.The blending of Ta enhanced surface wettability with prolonged contact time on the laser-machined line and rectangle microarrays.In vitro culture results showed beneficial effects of laser micropatterning on cell morphology of the fibroblasts.On the PCL/Ta surfaces with line and rectangle microarrays,the cells were more likely to bridge the sidewalls of the microgrooves,showing adaptive 3D morphologies to the micro/nano topographies on the sidewalls.These findings are envisaged to facilitate surface design and micropattern optimization for favorable tuning the cell response to biomedical PCL/Ta composites.