Abstract: This paper reports the heat-resistance of plasma electrolytic oxidation (PEO) coatings
formed on AZ91D alloy in phosphate electrolytes (P-film) and silicate electrolytes (Si-film). The
results showed that the P-film was mainly composed of MgAl2O4, MgO and the Si-film was
composed of Mg2SiO4, MgO. Thermoanalysis results verified that all these phases contained in the
two type coatings had excellent thermal stability below 800oC. Meanwhile, the total area of heat
erosion formed on the surface of samples tended to be increased with the exposure time prolonged in
high temperature (410 oC and air atmosphere).
Abstract: Structure and configuration of boundary dislocations on the low angle tilt grain boundaries
in alumina were considered based on the ideas that the boundary is composed of regularly arrayed
edge dislocations and that the dislocations could dissociate into partial dislocations as well as glide
dislocations in bulk. Moreover, the structure of the dissociated boundary dislocations were evaluated
by the calculations based on an elastic theory. The calculations indicated that the largeness of the
stacking fault region between partial dislocations formed by the dissociation will decrease with
increasing tilt angles. It can be said that the idea and calculations used here will be powerful in
considering the dislocation structure of low angle tilt grain boundaries that are not or are difficult to be
Abstract: Polyimide surfaces after macroscopic wear at 80 to 260°C are studied by atomic force
microscopy to give additional insight in the tribophysical and -chemical processes during sliding.
Three sliding regimes are distinguished with hydrolysis resulting in rough surfaces, imidisation
resulting in orientation of polymer molecules and melting resulting in short-range arrangements.
Abstract: In order to modify grain boundary character distribution (GBCD) and to improve
intergranualr corrosion (IGC) resistance of 304 stainless steel, laser surface remelting experiments
were conducted on 304 stainless steel using a 2kW CW Nd: YAG laser, and the effects of laser
processing parameters on GBCD and corrosion resistance were investigated in detail under the
optimal annealing condition (1220K 28h). The experimental results showed that combination of laser
surface remelting and the following annealing treatment could change the GBCD remarkably and
improve the IGC resistance of 304 stainless steel. However, there are no obvious effects of laser
processing parameters on the final depth of the processed zone, although the depth of the molten pool
increases with the increase of the laser output power or the decrease of the scanning velocity, and the
subsequent GBCD and corrosion resistance.
Abstract: Surface layer hardness and concentration profiles of austenitic stainless steels after
plasma carburizing and /or nitriding at 673 K were investigated. Carbon and nitrogen concentration
were measured by glow discharge optical emission spectrometry (GDOES) and carbides or nitrides
were detected by x-ray diffraction analysis (XRD) and TEM. The state of carbon at the treated
surface was investigated by Raman spectroscopy. Separation of carburized layer and nitrided layer
was observed in a simultaneous carburizing and nitriding plasma treatment.
Abstract: Interfacial microstructure of TiN-TiB2 composite, which was synthesized by hot shock
compaction combined explosively shock condolidation and self-propagating high-temperature
synthesis, was investigated by transmission electron microscopy (TEM). In the TiN-TiB2 composite
included 60mol% TiN, an experimentally measured average grain size of the both TiN and TiB2 was
approximately 500nm, and it decreased rather than those of the raw powders. By the conventional
TEM observations, we clarified that there was a specific orientation relationship between cubic TiN
and hexagonal TiB2. The high resolution electron microscopy (HREM) observations revealed that the
TiN/TiB2 interphase boudnaries were atomically flat. We also observed grain boundaries of the
composite and found that no secondary phases such as amorphous phase and precipitates were
observed at the grain boundaries in the composite.
Abstract: Water cavitation peening (WCP) with aeration is a recent promising method in the
surface enhancement technique, which can induce compressive residual stress in the near surface of
mechanical components by the bubble collapse on the surface of components in the similar way as
conventional shot peening. In this paper, the effect of WCP on fatigue crack growth behavior was
investigated in single-edge-notched flat tensile specimens of S45C steel. The notched specimens
were treated by WCP, and the compressive residual stress distributions in the near surface layer
were measured by X-ray diffraction method. The tension-tension (R = Smin/Smax = 0.1, f = 10 Hz)
fatigue tests were conducted. A Shimadzu servo-hydraulic fatigue test machine with in-situ
observation by JSM-5410LV scanning microscope was used for all testing. Compared with those
without WCP treatment, WCP can induce the residual compressive stress in the near surface layer,
and delay the fatigue crack initiation, and decrease the rate of fatigue crack growth.
Abstract: Deformation Induced Ferrite Transformation (DIFT), i.e. transformation occurs
during deformation applied in the temperatures above Ar3, has received wider
attention since it has been proved to be a very effective way to produce ultrafine
grained ferrite in low carbon steels. Although numerous works have been done on this
topic in the past decade, the systematic works on DIFT in microalloyed steel,
especially on the role of microalloying elements are still lacking compared with those
in plain carbon steel. In this paper, the common features of DIFT will reviewed firstly,
then an attempt will be made to elucidate the role of microalloying elements (niobium
and vanadium) in DIFT, and the application of DIFT technology in microalloyed
steels will be presented finally.