-
[show abstract]
[hide abstract]
ABSTRACT: Joining of composite, Al2O3-TiC, with heat-resistant 9Cr1MoV steel, was carried out by diffusion brazing technology, using a combination of Ti, Cu and
Ti as multi-interlayer. The interfacial strength was measured by shear testing and the result was explained by the fracture
morphology. Microstructural characterization of the Al2O3-TiC/9Cr1MoV joint was investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM) with energy-dispersion
spectroscopy (EDS). The results indicate that a Al2O3-TiC/9Cr1MoV joint with a shear strength of 122 MPa can be obtained by controlling heating temperature at 1130°C for 60 min
with a pressure of 12 MPa. Multi-interlayer Ti/Cu/Ti was fused fully and diffusion occurred to produce interfacial layer between
Al2O3-TiC and 9Cr1MoV steel. The total thickness of the interfacial layer is about 100 μm and Ti3AlC2, TiC, Cu and Fe2Ti are found to occur in the interface layer.
Bulletin of Materials Science 04/2012; 30(4):415-419. · 0.88 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Three different Cr–Ni alloys were deposited on the surface of Fe3Al intermetallic by shielded metal arc welding (SMAW) to investigate the weldability of this material. The microstructure,
phase constitutions, and fine structures of Cr–Ni surfacing layers were analyzed via metalloscope, SEM, XRD, and TEM. The
results indicated that the Fe3Al/Cr–Ni joint shows no cracks when Cr25–Ni13 alloy was deposited. The surfacing layer consisted of austenite (A), pro-eutectoid
ferrite (PF), carbide-free bainite (CFB), lath martensite (LM), and little acicular ferrite (AF). Phase constitutions of the
joint included Fe3Al, FeAl, γ-(Fe,C), γ-(Fe,Ni), NiAl, and Ni3Al. The lattice orientation for CFB between α and γ phases was (110)α//(111)
γ
. Typical LM was composed of interlayer-carbide and α ferrite of 400nm in length and 40nm in width.
Journal of Materials Science 01/2008; 43(4):1480-1485. · 2.02 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Fe3Al intermetallics and Q235 steel are bonded using vacuum diffusion bonding technology. The interfacial shear strength was
measured and the stress of Fe3Al/Q235 diffusion bonded joint was analyzed using finite element analysis (FEA). The results indicate that interfacial shear
strength increases from 39.9 to 112.3 MPa with the enhancement of heating temperature from 1000 to 1060°C. Also, shear fracture
has more characteristics of cleavage fracture. The farther from the central axis of the interface, the larger the stress is,
and the maximum stress appears on the surface of the joint. The maximum stress increases with the heating enhancement and
increase of material thickness. When the thickness reaches a critical value (6 mm) and then increases, the stress increases
slightly and even to a stable value.
Frontiers of Materials Science in China 04/2007; 1(2):215-219.
-
[show abstract]
[hide abstract]
ABSTRACT: The microstructure and phase constituent for the Mg/Al diffusion-bonded joint were studied via scanning electron microscope (SEM), microhardness test, electron probe microanalyzer (EPMA), and X-ray diffraction (XRD).
The test results indicated that the new compact phase was formed near the transition region of the Mg/Al diffusion interface.
There are three new phase layers in the transition region. The microhardness of the diffusion zone is higher than that of
the Mg and Al substrate. The fracture morphology mainly consists of a coarse and gray fracture, and the fracture is mainly
the mixed fracture of cleavage and intergranular. X-ray diffraction tests indicate that the diffusion zone of the Mg/Al diffusion-bonded
joint consists of intermetallic compounds MgAl, Mg3Al2, and Mg2Al3. With the increase of temperature, the content of Mg3Al2 and Mg2Al3 phases with good stability was increased.
Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science - METALL MATER TRANS B. 01/2006; 37(4):649-654.
-
[show abstract]
[hide abstract]
ABSTRACT: The microstructure near a diffusion interface was studied by means of scanning electron microscopy and electron probe microscopy, and the results indicated that the interface transition zone of Fe3Al/Q235 dissimilar materials was composed of a diffusion interface, a mixed transition region, and A/B transition regions at the sides of the interface. Microstructures of the interface and base materials were interlaced to form the microstructure of layer characteristic. With increased heating temperature and holding time, the width of the Fe3Al/Q235 interface transition zone increased and the microstructure gradually became coarse. The microhardness in the diffusion transition zone was decreased and there was a peak value at the diffusion interface. The distribution of Al, Fe, and Cr in the interface transition zone was increased or decreased monotonically with some local concentration fluctuation. There was nearly no change in the concentration of C element near the interface.
Journal of Colloid and Interface Science 09/2005; 288(2):521-5. · 3.07 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Fe3Al and Cr18-Ni8 stainless steel were diffusion-bonded in vacuum and a Fe3Al/Cr18-Ni8 interface with reaction layer was formed. Microstructure in the reaction layer at Fe3Al/Cr18-Ni8 interface was analyzed by means of scanning electron microscope (SEM) and electron probe micro-analyzer (EPMA). The growth of reaction layer with heating temperature (T) and holding time (t) was researched. The results indicate that FeAl, Fe3Al, Ni3Al, and alpha-Fe (Al) solid solution are formed in the reaction layer. These phases are favorable to promote the element diffusion and to accelerate the formation of the reaction layer at Fe3Al/Cr18-Ni8 interface. The growth of reaction layer obeys the parabolic law and its thickness (X) is expressed by X2 = 7.5 x 10(-4)exp(-83.59/RT)(t - t0).
Journal of Colloid and Interface Science 06/2005; 285(1):201-5. · 3.07 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Fe3Al and Cr18-Ni8 stainless steel were diffusion-bonded in vacuum and a Fe3Al/Cr18-Ni8 interface with reaction layer was formed. Microstructure in the reaction layer at Fe3Al/Cr18-Ni8 interface was analyzed by means of scanning electron microscope (SEM) and electron probe micro-analyzer (EPMA). The growth of reaction layer with heating temperature (T) and holding time (t) was researched. The results indicate that FeAl, Fe3Al, Ni3Al, and α-Fe (Al) solid solution are formed in the reaction layer. These phases are favorable to promote the element diffusion and to accelerate the formation of the reaction layer at Fe3Al/Cr18-Ni8 interface. The growth of reaction layer obeys the parabolic law and its thickness (X) is expressed by X2=7.5×10−4exp(−83.59/RT)(t−t0).
Journal of Colloid and Interface Science - J COLLOID INTERFACE SCI. 01/2005; 285(1):201-205.
-
[show abstract]
[hide abstract]
ABSTRACT: The microstructural characterization of Fe3Al/Q235 welded zone were analysed to investigate the welding behavior of Fe3Al intermetallic. The results indicated that a crack-free Fe3Al/Q235 joint was obtained when Cr25–Ni13 alloy was adopted as the filler metal. The microstructure of the welded zone presented different morphology due to the severe fluctuation of Al, Ni, Mn and Cr elements near the fusion zone. The fish-bone like structures in Q235 side fusion zone were composed of α-Fe(Cr, Al, Ni) solid solutions. Fe3Al/Q235 joint fractured in the Fe3Al HAZ, and shear strength of 533.33 MPa was achieved. The fracture mode of Fe3Al side fracture surface was mainly transgranular cleavage, occured along [1 1 1] orientation on {1 1 0} planes. And the Q235 side fracture surface was in intergranular and quasi-cleavage mode. The phase relations of γ and α in Fe3Al side fusion zone, constituent of lower bainite in the weld and the Fe3Al ordered transformation in HAZ were also determined.
Materials Chemistry and Physics 112(3):810-815. · 2.23 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Under welding condition, the co-existing microstructure of the B2 + DO3 domains is first observed in this article. The B2 → DO3 transformation in the heat affected zone (HAZ) can occur in two models: alternation transformation and precipitation transformation model depending on local dislocation density. And alternation model is the major model for the B2 → DO3 transformation. The brittleness and cracking-sensitivity of the Fe3Al are increased when alternation transformation model occurs. In precipitation transformation model, obtained fine DO3 domains can ensure sufficient toughness to avoid cracks. The formation mechanism of the dislocation loops in the fusion zone is discussed. And the stress concentration of the fusion zone can be released to some extent by the dislocation loops.
Materials Letters. 62:1953-1956.
-
[show abstract]
[hide abstract]
ABSTRACT: The microstructure and phase constitution near the diffusion bonding interface of Mg/Al dissimilar materials are studied using a scanning electron microscope (SEM), X-ray diffraction (XRD) and transmission electron microscope (TEM). The test results indicated that an obvious diffusion zone was formed near the Mg/Al interface during the vacuum diffusion bonding. The diffusion transition zone near the interface consists of various MgxAly phases. The transition region on the Mg side mainly consists of Mg crystals, and the new phase formed was the Mg3Al2 phase having a face-centred cubic lattice. This is favorable for improving the combined strength of Mg substrate and diffusion transition zone.
Vacuum. 82(1):15-19.
-
[show abstract]
[hide abstract]
ABSTRACT: A series of Cr–Ni alloys were overlaid on a Fe3Al surface by tungsten inert gas arc welding (TIG) technology. The microstructure of the Cr–Ni surface layers were analysed by means of optical metallography, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results indicated that when the appropriate TIG parameters were used and Cr25–Ni13 and Cr25–Ni20 alloys were used for the overlaid materials, the Cr–Ni surface layers were crack-free. The matrix of the surface layer was austenite (A), pro-eutectoid ferrite (PF), acicular ferrite (AF), carbide-free bainite (CFB) and lath martensite (LM), distributed on the austenitic grain boundaries as well as inside the grains. The phase constituents of the Cr25–Ni13 surface layer were γ-Fe, Fe3Al, FeAl, NiAl, an Fe–C compound and an Fe–C–Cr compound. The microhardness of the fusion zone was lower than that of the Fe3Al base metal and Cr25–Ni13 surface layer.
Materials Characterization.
