Age-hardening behavior and microstructure of Cu-15Ni-8Sn-0.3Nb alloy prepared by powder metallurgy and hot extrusion

Cu-15Ni-8Sn-0.3Nb alloy rods were prepared by means of powder metallurgy followed by hot extrusion.Element maps obtained by electron probe micro analyzer(EPMA)showed that Nb-rich phases were formed and distributed within grains and at grain boundaries of the Cu-15Ni-8Sn-0.3Nb alloy.Transmission electron microscope(TEM)results indicated that there was no obvious orientation relationship between these phases and the matrix.Spinodal decomposition and ordering transformation appeared at early stages of aging at400°C and caused significant strengthening.Cu-15Ni-8Sn-0.3Nb alloy exhibited both higher strength(ultimate tensile strength>1030MPa)and higher tensile ductility(elongation>9.1%)than Cu-15Ni-8Sn alloy after aging treatment.The improvement was caused by Nb-rich phases at grain boundaries which led o the refinement of grain size and postponed the growth of discontinuous precipitates during aging.

Improved mechanical proprieties of“magnesium based composites”with titaniume-aluminum hybrids

In this study,the effect of micron-sized titanium and aluminum addition on the microstructural,mechanical and work-hardening behavior of pure Mg is investigated.Pure Mg reinforced with 10%Ti and 10%Ti-1%Al particulates were synthesized through semi-powder metallurgy route followed by hot extrusion.Semi-powder metallurgy appears to be promising approach for the synthesis of Mg based composite,as it is free of ball milling.Tensile results indicate that the direct addition of micron-sized 10wt.%titanium particulates to pure Mg,caused an improvement in elastic modulus,0.2%yield strength,ultimate tensile strength,and failure strain(+72%;+41%;+29%;and+79%respectively).The addition of micron-sized 10wt.%titanium particles along with 1.0wt.%Al particles to pure Mg,resulted in an enhancement in elastic modulus,0.2%yield strength,ultimate tensile strength,and failure strain(+74%;+56%;+45%;and+241%respectively).Besides tensile test,Vickers hardness and work-hardening behavior of prepared composites were also examined.Impressive failure strain of Mg-10Ti-1Al composite can be attributed to the better compatibility of Ti particulates with Mg due to presence of alloying element Al.

Effect of graphene oxide on the corrosion,mechanical and biological properties of Mg-based nanocomposite

This study investigates the effect of graphene oxide(GO)on the mechanical and corrosion behavior,antibacterial performance,and cell response of Mg–Zn–Mn(MZM)nanocomposite.MZM/GO nanocomposites with different amounts of GO(i.e.,0.5 wt%,1.0 wt%,and1.5 wt%)were fabricated by the semi-powder metallurgy method.The influence of GO on the MZM nanocomposite was analyzed through the hardness,compressive,corrosion,antibacterial,and cytotoxicity tests.The experimental results showed that,with the increase in the amount of GO(0.5 wt%and 1.5 wt%),the hardness value,compressive strength,and antibacterial performance of the MZM nanocomposite increased,whereas the cell viability and osteogenesis level decreased after the addition of 1.5 wt%GO.Moreover,the electrochemical examination results showed that the corrosion behavior of the MZM alloy was significantly enhanced after encapsulation in 0.5 wt%GO.In summary,MZM nanocomposites reinforced with GO can be used for implant applications because of their antibacterial performance and mechanical property.