Showing papers by "Vincent Ji published in 1998"

The influence of Nb ion implantation upon oxidation behavior and hardness of a Ti-48 at.% Al alloy

Abstract: The influence of Nb ion implantation with different doses upon microhardness and high-temperature oxidation resistance of a Ti-48 at.% Al alloy was investigated. The results showed that the surface microhardness of the alloy was significantly increased by Nb implantation with doses from 3 × 10 15 ions cm −2 to 3 × 10 16 ions cm −2 , and reached a constant level at a dose of 3 × 10 17 ions cm −2 . The isothermal oxidation resistance of the alloy at 900 °C and 950 °C in an atmospheric environment could be remarkably improved by Nb ion implantation with a dose of 3 × 10 17 ions cm −2 , which was attributed to the effect of the implanted Nb atoms on the nucleation and formation of the oxides and the oxidation scale microstructure. The influence of both the primary and secondary effects of Nb ion implantation upon the microhardness and oxidation behavior of Ti-48 at.% Al alloy is discussed.

Influence of shot peening on superficial yield strength of spring steel in hard state

Abstract: The yield strength of a metallic technological surface with biaxial residual stresses may be determined using X-ray stress analysis techniques. Shot peening can increase the superficial proof stresses of a spring steel treated in the hard state, even though there is a considerable decrease in the half width of the X-ray diffraction profile. It can therefore be concluded that for a metallic material in the hard state, the half width parameter of the X -ray interference lines at the surface does not correctly reflect static strength.