Zr Filler Research Articles

Microstructure and properties of C/C and C/SiC composites brazed by reactive infiltration of Si[sbnd]Zr filler alloy

The joint between C/C composites and liquid silicon infiltrated-C/SiC composites was achieved using a Si10Zr (at. %) eutectic filler. The microstructure and mechanical properties of joints at different brazing temperature and holding time were characterized. The results showed that the melting filler infiltrated along the carbon fiber bundle gaps and formed SiC reaction layers at both interfaces. On the side of C/SiC composites, the residual silicon in the original base material dissolved into the molten Si10Zr alloy during the brazing procedure. The phenomenon resulted in intense infiltration of the liquid filler into C/SiC composites, which formed a unique C/SiC-Si-ZrSi2 multiphase-ceramic gradient structure. Excessive filler was squeezed out around the joint seam to form a fillet. The shear strength of the joint reached up to 37 MPa, with fracture occurrence in both substrates and the joint seam. Reliable bonding between C/C and C/SiC dissimilar composites was finally achieved.

Vacuum brazing of biomedical TNZ alloy to ZrO2 ceramic using Sn–Zr filler: interfacial microstructure and mechanical properties

Vacuum brazing of biomedical TNZ alloy to ZrO2 ceramic using Sn–Zr filler: interfacial microstructure and mechanical properties

Microstructure and mechanical properties of Cu/Al joints brazed using (Cu, Ni, Zr, Er)-modified Al—Si filler alloys

To design a promising Al—Si filler alloy with a relatively low melting-point, good strength and plasticity for the Cu/Al joint, the Cu, Ni, Zr and Er elements were innovatively added to modify the traditional Al—Si eutectic filler. The microstructure and mechanical properties of filler alloys and Cu/Al joints were investigated. The result indicated that the Al—Si—Ni—Cu filler alloys mainly consisted of Al(s,s), Al2(Cu,Ni) and Si(s,s). The Al—10Si—2Ni—6Cu filler alloy exhibited relatively low solidus (521 °C) and liquidus (577 °C) temperature, good tensile strength (305.8 MPa) and fracture elongation (8.5%). The corresponding Cu/Al joint brazed using Al—10Si—2Ni—6Cu filler was mainly composed of Al8(Mn,Fe)2Si, Al2(Cu,Ni)3, Al(Cu,Ni), Al2(Cu,Ni) and Al(s,s), yielding a shear strength of (90.3±10.7) MPa. The joint strength was further improved to (94.6±2.5) MPa when the joint was brazed using the Al—10Si—2Ni—6Cu—0.2Er—0.2Zr filler alloy. Consequently, the (Cu, Ni, Zr, Er)-modified Al—Si filler alloy was suitable for obtaining high-quality Cu/Al brazed joints.

The microstructure and weldability in welded joints for AA 5356 aluminum alloy after adding modified trace amounts of Sc and Zr

Abstract Different AA5356 alloy filler metals containing various amounts of Sc and Zr are obtained and applied to join the 5083 aluminium plate with 2.8 mm thickness. A significant grain refinement can be observed in the fusion zone (FZ) of welded joints after the additions of Sc and Zr. The filler metal modified with 0.2 wt.% Zr+0.1 wt.% Sc obtained the smallest grain size with 29 μm, and the filler metal with 0.2 wt.% Sc+0.1 wt.% Zr additions got the similar grain size with 30 μm. The 0.2 wt.% Sc addition can effectively modify the microstructure of filler metal and improve the mechanical properties. The grain size of fusion zone for AA5356 + 0.2 wt.% Sc+0.1 wt.% Zr filler metal decreased by 75.8 % and the highest ultimate tensile strength (UTS) increases by 15 % compared with the unmodified alloy joints. However, individual 0.2 wt.% Zr addition cannot effectively modify the filler metal. The improvement of mechanical properties can attribute to the presence of refined grains.

Microstructure evolution and mechanical properties of Ti2AlNb/TiAl brazed joint using newly-developed Ti–Ni–Nb–Zr filler alloy

Joining of Ti2AlNb alloy to TiAl intermetallics was conducted by the newly-developed Ti–Ni–Nb–Zr brazing filler alloy. The microstructure evolution of the joints was investigated by scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and electron backscatter diffraction (EBSD). The macro-micro mechanical properties were studied by shear test and nano-indentation test. Typical interfacial microstructures across the brazing seam were Ti2AlNb substrate, α2-Ti3Al+β-Ti, γ-TiAl+Ti2Ni+TiNi+α2-Ti3Al, α2-Ti3Al+β-Ti, TiAl substrate. The Ti2Ni phase were firstly dissolved in the joints brazed at 1000 °C for 10 min and then precipitated after a prolonged holding time of 15 min. The nano-indentation test revealed that Ti2Ni phase exhibited the highest hardness of 12.60 GPa. The joints brazed at 1000 °C/15 min presented the maximum shear strength of 271 MPa. The dissolution and precipitation behavior of Ti2Ni phase was also discussed.

An Impact of Zirconium Doping of Zn-Al Braze on the Aluminum-Stainless Steel Joints Integrity During Aging

This work offers an analysis of the microstructure and the growth rate of an intermetallic compound within the aged AA 6061 aluminum alloy-304 stainless steel joint brazed with Zn-15Al and Zn-15Al-0.2Zr filler metals. The effect of zirconium addition on mechanical integrity of the brazed joint was studied. The experimental results confirm that the thickness of the Fe-Al intermetallic layer formed at the brazed seam/stainless steel interface increases with the increase of the aging time. Furthermore, it is established that the growth rate of the intermetallic layer for the Zn-15Al-0.2Zr brazed joint was lower than that for Zn-15Al. The results also indicate that the shear strength of both Zn-15Al and Zn-15Al-0.2Zr brazed joints decreases monotonously during aging. The value of the strength after aging lasting for 800 h for Zn-15Al and Zn-15Al-0.2Zr has decreased by 20 and 17%, respectively. The fracture of joints occurred at the interface between the brazed seam and the Fe4Al13 intermetallic layer. The morphology of the surfaces exhibits a cleavage fracture.

Fracture resistance of endodontically treated teeth restored with Zirconia filler containing composite core material and fiber posts

Objectives:To assess the fracture resistance of endodontically treated teeth with a novel Zirconia (Zr) nano-particle filler containing bulk fill resin composite.Methods:Forty-five freshly extracted maxillary central incisors were endodontically treated using conventional step back preparation and warm lateral condensation filling. Post space preparation was performed using drills compatible for fiber posts (Rely X Fiber Post) on all teeth (n=45), and posts were cemented using self etch resin cement (Rely X Unicem). Samples were equally divided into three groups (n=15) based on the type of core materials, ZirconCore (ZC) MulticCore Flow (MC) and Luxacore Dual (LC). All specimens were mounted in acrylic resin and loads were applied (Universal testing machine) at 130° to the long axis of teeth, at a crosshead speed of 0.5 mm/min until failure. The loads and the site at which the failures occurred were recorded. Data obtained was tabulated and analyzed using a statistical program. The means and standard deviations were compared using ANOVA and Multiple comparisons test.Results:The lowest and highest failure loads were shown by groups LC (18.741±3.02) and MC (25.16±3.30) respectively. Group LC (18.741±3.02) showed significantly lower failure loads compared to groups ZC (23.02±4.21) and MC (25.16±3.30) (p<0.01). However groups ZC (23.02±4.21) and MC (25.16±3.30) showed comparable failure loads (p=0.23).Conclusions:Fracture resistance of endodontically treated teeth restored with Zr filler containing bulk fill composite cores was comparable to teeth restored with conventional Zr free bulk fill composites. Zr filled bulk fill composites are recommended for restoration of endodontically treated teeth as they show comparable fracture resistance to conventional composite materials with less catastrophic failures.

Modeling and simulation of the TiC reaction layer growth during active brazing of diamond using DICTRA

The growth kinetics of the TiC reaction layer during active brazing of diamond with Cu–Sn–Ti and Ag–Cu–Ti based filler alloy has been investigated by kinetic simulations and comparing with available experimental data. First, to obtain a reliable mobility database, the atomic mobilities of C and Ti in fcc (face-centered cubic) TiC are assessed using software DICTRA based on available diffusion data from literatures. Then, to carry out simulations for GB (Grain Boundary) diffusion in TiC, the bulk activation energy multiplier is determined by evaluating the available GB diffusion data. With the obtained mobility data, the TiC growth for Cu–Sn–Ti–Zr filler as a function of brazing temperature and time is simulated using various possible GB diffusion parameters. Afterwards, the determined GB diffusion parameters are validated by simulating the TiC growth for various Cu–Sn–Ti or Ag–Cu–Ti brazing alloys and comparing the simulated results with experimental data. Based on the optimized GB diffusion parameters, the influence of brazing temperature, filler alloy composition, and braze layer thickness on growth kinetics of TiC are simulated and discussed. Finally, the experimentally observed segregation of Cu at the interface between diamond and TiC layer during brazing of diamond using Cu–Sn–Ti or Ag–Cu–Ti filler is analyzed by diffusion simulations.

Influence of Zr addition on TIG welding–brazing of Ti–6Al–4V toAl5A06

TIG welding–brazing of Ti–6Al–4V to Al5A06 alloys with pure Al and Al–Cu–Zr fillers was investigated. The Zr and Cu additions enhanced the spreadability of Al-based fillers on Ti–6Al–4V substrate under TIG heating condition, and a sound Ti/Al dissimilar butt joint was obtained. Influenced by Zr addition, a discontinuous TiAl3 layer with a thickness of 2–4μm was observed at the Ti/seam interface under a low heat input condition, which was replaced by TiAl3+L–(Ti,Zr)Al3+H–(Ti,Zr)Al3 multi-sublayers when a high heat input was adopted. The joint with Al–Cu–Zr filler has higher tensile property and wider processing parameters than that with pure Al filler. The largest tensile strength of the joint produced by Al–Cu–Zr filler reaches 284MPa up to 85% of base Al5A06 alloys, and the fracture occurred by quasi-cleavage mode at the TiAl3 sublayer. Zr addition was favorable to enhance the spreadability on Ti substrate, and the welding processing parameters were broadened by the presence of Zr addition.

Interfacial morphology and strength of Al2O3/Nb joint brazed with Cu -Ti -Zr filler metal

In the present work ceramic Al2O3 was brazed to Nb using Cu -Ti- Zr as filler metal. The morphologies and chemical compositions of the phases formed were studied by SEM combined with energy dispersive spectroscopy and X-ray diffraction. It was found that the interfacial structure of joints brazed with Cu70Ti25Zr5 filler metal at 1293 K for 10 min was Al2O3/Cu2Ti4O/Nb solid solution/CuTi/Cu solid solution + CuTi with the formation of the new phases Cu2Ti4O, Ti solid solution, and CuTi. The joint strength was investigated using a tensile/shear testing machine. According to the experimental results, an Al2O3/Cu70Ti25Zr5/Nb joint brazed at 1293 K for 10 min can support a stress of 162 MPa. For lower contents of Ti and lower bonding times, or higher contents of Ti and higher bonding times, the strength of the joint was lower than the above value.

Interfacial Reactions between Cu-Zr filler metal and alumina and kinetics of reaction layer growth

The interfacial reactions and kinetics of the reaction layer growth in Cu-Zr/A12O3 system were investigated and compared with those in Cu-Ti/Al2O3 system. Therrnodynamic analysis showed that the interfacial reaction can proceed until the activity of aluminum in the Cu-5 at.% Zr filler metal reaches about 0.27 at 1373 K. Growth of reaction layer, ZrO2, was controlled by the diffusion of oxygen through ZrO2 layer. The activation energy for ZrO2 growth was 126 kJ/mol. Instead of using a complex redox reaction, a simple oxidation model between reactive metal and oxygen was found to adequately describe the reaction layers growth in ceramic/metal systems. The parabolic rate constant could be expressed in terms of oxygen vacancy concentration at the reactive metal/reactive metal oxide interface. The slower growth of TiO, in comparison with ZrO2, can be rationalized using the parabolic rate constant. The lower diffusion coefficient of oxygen vacancy and a less negative free energy change of TiO formation have a dominant effect over the higher oxygen vacancy concentration at the Ti/TiO interface which resulted in slower TiO growth.

Evaluation of the strength of diffusion bonded joints in continuous fiber reinforced metal matrix composites

SiC continuous fiber reinforced Ti6Al4V composites with various fiber volume fractions were fabricated by the vacuum hot pressing process and were joined to a Ti6Al4V alloy plate by solid state diffusion bonding processes. The matrix alloy was perfectly joined to the Ti6Al4V plate within the bonding condition. The joint strength decreased with increasing fiber volume fraction. The joint strength was not directly proportional the matrix area fraction. A joint efficiency over 90% could be obtained when the fiber volume fraction was less than 30%. The SiC fibers were debonded from the matrix and cylindrical defects were formed at the end of the fiber under tensile stress. The defects produced a triaxial stress state at the matrix alloy and thus higher joint strengths than the values simply calculated from the area fraction of the matrix at the bonding interface. The composite was transient liquid phase bonded to itself using TiCuZr filler metal. The joint strength was degraded using thin interlayer less than 80 μm thick. An interlayer thickenss over 80 μm was found to be necessary to obtain a sound joint.