Abstract: Recently, a new super-high-strength Al-Zn-Mg-Cu alloy with Zr bearing was developed in
BIAM. In this paper, the effect of microalloying element Zr on the microstructure and mechanical
properties of the alloy was investigated. It was found that the influence of Zr on the microstructure
and age-hardening behaviors was remarkable. The strength of the alloy increases with increasing the
content of zirconium, and the peak value of the elongation appeared when the content of Zr was
0.06%(mass fraction) and then decreases. The fracture behavior was also studied. The result shows
that the fracture mechanism of the alloy was converted from intergranular brittle to transgranular
ductile model with increasing the content of zirconium. Finally, the optimum contents of Zr in the
alloy were proposed as 0.10%~0.14%.
Abstract: Large extrusion and forgings of Al-9Fe-1.9Mo-1.7Si (wt.%, FMS0918) aluminum alloy for
elevated temperature applications were produced by rapidly solidified powder metallurgy process.
Powders of FMS0918 alloy were produced by inert gas atomization, and then screened, canned,
degassed, extruded and forged. The extrusion exhibited good strengths and elongation in longitudinal
orientation, but low elongation in long- and short-transverse orientations. After forged, the tensile
strengths of the forgings showed little change, but the long- and short-transverse elongation was
Abstract: The flow field and gas-bubble size during the process of aluminum melt degassing were
investigated in water model. A Φ400mm×400mm transparent water model and an impellor degassing
device were used in this study. The instantaneous velocity fields of water and bubbles under the
mixture of rotary injector were measured with PIV velocity field measurement technique. Then the
pictures of bubbles gained from PIV were analyzed with software to get the bubble size distribution.
The results showed that bubble flow field and bubble size were influenced by rotary speed of rotor and
gas flow-rate. With the increase of rotary speed of rotor, the horizontal velocity components of
bubbles became larger, the stagnant time of bubbles in water increaseed correspondingly and bubble
size became smaller. With the increase of gas flow-rate, the longitudinal velocity components of
bubbles became larger, the stagnant time of bubbles in water decreased correspondingly, and the
bubble size became larger also.
Abstract: Corrosion performances of several metallic materials (Al6061 and Al319 alloys, 304
stainless steel and grey cast iron) in the ethanol-gasoline alternative fuels were investigated. Cyclic
potentiodynamic polarization tests were used to study their corrosion behavior. Anodizing and
plasma electrolytic oxidation (PEO) techniques were used to produce oxide coatings on the Al6061
and Al319 alloys, and the corrosion properties of these coatings in the alternative fuel environments
were also evaluated. The results showed that, the 304 stainless steel, Al6061 and the coating materials
are compatible with the alternative fuels. The oxide coatings on both Al alloys provided effective
corrosion protection in the alternative fuel environments.
Abstract: 2024-T6 Al alloy sheet s were modified by bis-[triethoxysilylpropyl] tetrasulfide
(BTESPT) silane film to improve the corrosion resistance. Fourier-Transform Reflection Absorption
(FTIR-RA) spectroscopy was used for structural characterization of BTESPT silane film formed on
surface of the sheet. Potentiodynamic polarization and immersion test in 3.5% NaCl solution were
used for evaluating the corrosion performances of the silane film. The results showed that the film
formed after curing at 120 °C for 40 min was cross-linked through Si-O-Si and that it was covered on
the entire surface of the sheet. The content of elements S and Si on the Al2CuMg particles is a little
higher that of on the matrix. The strong peak at 1032 cm-1 indicated that the film was linked to the
sheet by Si-O-Al. Compared to the untreated case, the corrosion current density of the sheet treated
with the silane film was reduced by close to 2 orders. Treatment of BTESPT silane can provide about
670 h protection of corrosion for the sheet in 3.5% NaCl water solution.
Abstract: The effect of pre-rolling reduction prior to ageing on the size and distribution of the
precipitates, the width of precipitation free zones (PFZ) along grain boundaries and intergranular
corrosion (IGC) of aluminum alloy 2519A were investigated by hardness tests, scanning electron
microscopy (SEM) and transmission electron microscopy (TEM). The experimental results showed
that the time for peak-age shortened when the reduction increased, which resulted in refining the
precipitatates and distributing homogeneously within the grains and hence the IGC decreased. With
increasing pre-rolling reduction, the PFZ along grain boundaries became narrower and precipitates
changed from continuous chains to discrete distribution, which resulted in high IGC resistance.
Abstract: The corrosion behavior of cold worked Al-Mg-Sc-Zr-Ni alloys prepared by vacuum
induction melting in acidic chloride solution was studied. The morphological characteristics of the
corroded specimens were examined by OM(optical microscopy), SEMand EDX techniques. The
results indicated that the intergranular and exfoliation corrosion susceptibility dramatically depended
on the Ni content. The Al-Mg-Sc-Zr alloy with 0 and 0.5 wt.% Ni were lightly susceptible to
intergranular corrosion as the precipitation of Mg2Al3 phases presented at grain boundaries and the
Al3Ni particles were finely dispersive. The intergranular corrosion was enhanced by the Al3Ni
particles enrichment and became pitting corrosion with increasing Ni to 1.0 wt.%. Finally, the
exfoliation corrosion happened to the alloy with 2.0wt.% Ni. This trend correlated well with the
electrochemical property and distribution of Al3Ni phases. The corrosion potential of Al3Ni
intermetallic phase is nobler than the β phase and the matrix, which result in an appearance of
galvanic coupling. In addition, the increase of Al3Ni particles enlarged the attack area and the
inhomogeneous segments of Al3Ni and Al3Mg2 phases accelerated the localized corrosion.
Abstract: After surface mechanical attrition treatment (SMAT) for Al-Zn-Mg alloy, a gradient
structure with average grain size increased from 20nm in surface layer to about 100nm at a depth of
20μm was formed. The thermal stability of surface nanostructured layer in Al-Zn-Mg alloy samples
was investigated by vacuum annealing at 100°C, 150°C, 200°C and 250°C for 1h, respectively. The
microstructural evolution as well as the microhardness along the depth from top surface layer to
matrix of SMATed samples was analyzed. Experimental results showed that the grain size of surface
nanocrystallites remains in submicro-scale, ranging from 300nm to 400nm, when annealed at a
temperature of 250°C, and the microhardness of surface nanostructured layer was still high compared
with that of matrix, indicating satisfying thermal stability of nanocrystallized layer. This might be
attributed to the presence of substantive trident grain boundaries and pinning effect of dispersive
precipitated phases in nanocrystalline materials, which hindered the grain boundary migration that
leading to grain growth.
Abstract: The surface roughness and morphology of the ceramic coatings fabricated on industrially
pure aluminum by the plasma electrolytic oxidation (PEO) technique with a hetero-polar pulsed
current ceramic synthesizing system were investigated. A model for the process was established.
Based on this a formula was deduced to estimate the temperature rise rate at the corresponding
locations before the plasma discharge channels have formed during the PEO process, and the
channels’ temperature when the plasma discharges occur. Results show that the PEO ceramic
coatings grow by an alternating coating melting and solidifying way; The coating roughness becomes
greater and the plasma discharge channel population in the ceramic coatings decreases while the pores
enlarge with PEO treatment time and current. With the deduced formula, the PEO alumina coating on
industrially pure aluminum was taken as an example for validation of the model.