Injection Casting Technique Research Articles

Magnetic and structural properties of nanocomposite permanent magnet produced from crystallization of Pr4Fe67Nb4Cu2Zr1B22 alloy

Present research work narrates synthesis, structural, thermal and magnetic characteristics of Pr4Fe67Nb4Cu2Zr1B22 nanocomposite magnets. Amorphous Pr4Fe67Nb4Cu2Zr1B22 rods were produced through injection casting technique and permanent magnetic characteristics were obtained by one-step annealing the amorphous rods. XRD analysis elucidated that as-cast rods have amorphous phase structure and annealed magnets have tetragonal Pr2Fe14B hard phase, cubic structural α-Fe phase and tetragonal Fe3B soft phase. Optimal annealed magnet composed of 63% Pr2Fe14B hard phase, 26% α-Fe and 11% Fe3B soft phases with mean grain sizes around 51.6 ± 1 nm for Pr2Fe14B, 25.4 ± 2 nm for α-Fe and 21.5 ± 2 nm for Fe3B phases. Microscopic and atomic probe studies showed that the annealed magnet consists of Pr2Fe14B, α-Fe, Fe3B nanosized grains interlinked with thin grain boundaries. Henkel curve evidenced the existence of inter-grain exchange coupling between magnetic nanophase grains. Magnetic hysteresis measurements revealed that Pr4Fe67Nb4Cu2Zr1B22 nanocomposite magnet yielded maximum magnetic characteristics such as coercivity Hc of 382 kA/m, remanence Br of 0.70 T and maximum energy product (BH)max of 64.2 kJ/m3 with rare earth to iron ratio 4:67.

Preliminary study of fabrication technology for transmutation fuels using surrogate alloy

A preliminary study on the fabrication of transmutation fuels was carried out using an injection casting technique. Melts of binary U–Zr, a surrogate alloy for transmutation fuels, with high Zr contents (15, 20, and 25 wt%) were mixed via electromagnetic stirring, and fuel slugs were successfully cast to the full length of the mold without macrodefects. From chemical composition analysis by ICP-AES, the Zr content of the U–Zr slugs matched well with the target composition, to within 5% difference. The microstructure examined by SEM showed that with an increase in the Zr concentration, the lamellar structure was reduced, and Zr-rich inclusions were uniformly distributed over the fuel slugs.

Nanocomposite Nd-Y-Fe-B-Mo bulk magnets prepared by injection casting technique

The phase composition, magnetic and microstructural properties of Nd2Fe14B/(α-Fe, Fe3B) nanocomposite magnets produced by injection casting technique have been studied. Magnetic hysteresis loop of the Nd7Y6Fe61B22Mo4 permanent magnet demonstrates the coercivity as high as 1289kA/m. Electron microscopy elucidates a microstructure composed of magnetically soft α-Fe, Fe3B and hard Nd2Fe14B/Y2Fe14B nanograins (20–50nm) separated by ultra-thin grain boundary layer. The Henkel plot curve of the Nd7Y6Fe61B22Mo4 magnet yields the existence of exchange coupling interactions between soft and hard phases. Macroscopically large size sheet magnet is obtained due to high glass forming ability of the Nd7Y6Fe61B22Mo4 alloy derived from large atomic radius mismatch and negative enthalpy of alloy constituent elements. The high coercivity of the magnet is attributed to the magnetically hard phase increment, nucleation of reverse domains and the presence of thin grain boundary phase. Good magnetic properties such as remanence of 0.51T, coercivity of 1289kA/m and maximum energy product of 46.2kJ/m3 are obtained in directly casted Nd7Y6Fe61B22Mo4 sheet magnets.

Microstructure and room temperature mechanical properties of NiAl–Cr(Mo)–(Hf, Dy) hypoeutectic alloy prepared by injection casting

The NiAl–Cr(Mo)–(Hf,Dy) hypoeutectic alloys were prepared by conventional casting and injection casting techniques respectively, and their microstructure and room temperature mechanical properties were investigated. The results reveal that with the addition of Hf and Dy, the Ni2AlHf Heusler phase and Ni5Dy phase form along the NiAl/Cr(Mo) phase boundaries in intercellular region. By the injection casting method, some Ni2AlHf Heusler phase and Ni5Dy phase transform into Hf and Dy solid solutions, respectively. Moreover, the microstructure of the alloy gets good optimization, which can be characterized by the fine interlamellar spacing, high proportion of eutectic cell area and homogeneously distributed fine Ni2AlHf, Ni5Dy, Hf solid solution and Dy solid solutions. Compared with conventional-cast alloy, the room temperature mechanical properties of injection-cast alloy are improved obviously.

Magnetic and magnetocaloric properties of ternary Gd–Co–Al bulk metallic glasses

Bulk metallic glasses (BMGs) with compositions of Gd 55Co x Al 45− x (15 ≤ x ≤ 30) and Gd 60Co y Al 40− y (15 ≤ y ≤ 30) were synthesized by an injection casting technique. Temperature dependence of magnetization of the BMGs indicates that their Curie temperatures can be tailored between 96 and 143 K by varying Gd and Co concentration. The magnetic entropy changes of the BMGs are greater than 9.0 J/kg K except for the Gd 55Co 30Al 15 glass that exhibits a reduced magnetization due to its large Co content. The relative cooling powers of the BMGs are greater than those of any other crystalline compounds and decrease with the increasing Co content.

Magnetic properties of bulk composite FeBSiM (M=Cr,Zr) alloys with high microhardness

AbstractThe synthesis, mechanical and magnetic properties of bulk composite Fe72B19.2Si4.8M4 (M=Cr, Zr) alloys obtained by a copper mould injection casting technique under a protective helium atmosphere are reported and discussed. The resultant microstructure of the composite alloys consists of crystalline Fe92Si8 and Fe2B phases embedded in a glassy matrix. The values of microhardness (Hv) show maxima for the alloy containing Cr with 10.24±0.95 GPa. The maximum value of saturation magnetization average (μ0Ms) is 1.25±0.02 T for Cr-containing alloy. The Curie temperatures (Tc) of amorphous phases are higher than 390 K for both alloys. However, the bulk composite alloys presents values for crystallization temperature (Tx) of 1289±10 K and 1140±10 K for Cr and Zr-containing alloys, respectively. These results are interpreted on the basis of the interplay between the crystalline and amorphous phases.

Magnetic power losses in [(Fe1-xCox)75B20Si5]93Nb4Y3 (x = 0, 0.2, 0.4) bulk metallic glasses

Magnetic power losses of [(Fe1-xCox)75B20Si5]93Nb4Y3 (x = 0, 0.2, 0.4) metallic glasses have been investigated. Bulk samples were prepared by water-cooled Cu-mold injection casting technique with shapes of cylinders (0.8 mm diameter and 30 mm length) and toroids (10 mm external diameter and 0.5 mm thickness). Ribbons prepared by the melt- spinning technique were also analyzed. Glassy structures were confirmed by the presence of a main halo in XRD and by crystallization signal in DSC. Power losses were studied with a digital wattmeter over a range of frequencies from 1 to 400 Hz at selected peak inductions. Ribbons show smaller losses than bulk samples, presenting 24.5 J/m3 at 50 Hz and 0.65 T peak induction. It was observed that the Co addition reduces significantly the power losses. A separation theory was applied in order to explain the square root behavior of the measured power losses as a function of frequency and the results are in good agreement with the experimental data. The magnetic data were used to identify the presence of crystalline inclusions in the magnetic bulk metallic glasses. The effect of sample shape and composition on magnetic properties will be discussed.

Magnetic properties of Fe–Co-based bulk metallic glasses

Amorphous [(Fe 1− x Co x ) 75B 20Si 5] 93Nb 4Y 3( x = 0 , 0.2 and 0.4) have been produced by water-cooled Cu-mold injection casting technique in cylindrical shape. Amorphous ribbon having the same composition have been produced by rapid quenching technique. The presence of an amorphous structure have been checked by means of X-ray diffraction measurements and differential scanning calorimetry. Magnetic hysteresis loops have been measured by means of vibrating sample magnetometer at a maximum field of 10 kOe. In addition, to study the frequency dependence of magnetic losses, hysteresis loops have been measured by a digital wattmeter. A critical analysis of the results obtained on both ribbons and bulk cylinder will be presented. The obtained data will be compared with the ones of Fe-based materials conventionally exploited in applications.

Microstructure and mechanical properties of rapidly solidified NiAl–Cr(Mo) eutectic alloy doped with trace Dy

The Ni–33Al–28Cr–6Mo eutectic alloy doped with trace Dy was prepared by conventionally casting and injection casting techniques. Microstructure examination revealed that with the addition of Dy, the Ni 5Dy phase precipitated along the NiAl and Cr(Mo) phases interface in the intercellular region. Compared with the conventional-cast alloy, the microstructure of injection-cast alloy got well optimized, which was characterized by the thin interlamellar spacing, high proportion of eutectic cell area and fine homogeneous distributed Ni 5Dy phase. Furthermore, the mechanical tests showed that the room temperature mechanical properties of the injection casting alloy improve significantly.

Magnetic properties and power losses in Fe–Co-based bulk metallic glasses

Magnetic properties of Fe–Co-based bulk metallic glasses have been experimentally investigated. Samples were prepared by water-cooled Cu-mold injection casting technique. The samples have cylindrical shapes with 0.8 mm diameter and 30 mm length. Amorphous structures were confirmed by the presence of a main halo in X-ray diffraction patterns and by the detection of crystallization signal around 650 °C using differential scanning calorimetry. Owing to their amorphous structure, these materials present good soft magnetic properties with coercivity below 100 A/m and magnetic induction around 1.0 T in quasi-static conditions. Hysteresis loops were measured using a digital wattmeter with controlled induction waveform. Power losses were analyzed for the following compositions: [(Fe 1− x Co x ) 75B 20Si 5] 93Nb 4Y 3 ( x=0, 0.2, 0.4, 0.5 and 0.6) over a range of frequencies from 1 to 400 Hz at selected fixed peak inductions. Co addition has shown to improve the soft magnetic properties when x=0.2, 0.4 and 0.5, decreasing coercive fields and power losses, while the magnetic induction is slightly increased (except for x=0.5). Further Co addition ( x=0.6) is detrimental for the soft magnetic properties due to the presence of crystalline α-Fe–(Co) and boride phases. The frequency dependence of power losses was described using a separation theory. It has been observed that an f 1/2 rule is in good agreement with the experimental data.

Influence of Co Addition on Magnetic Properties and Glass Formation of Fe-based Amorphous Alloys

AbstractIn the present work, the influence of Co addition on the glass forming ability (GFA) and magnetic properties of the ((Fe1−xCox)75B20Si5)93Nb4Y3 (x = 0, 0.2, 0.4, 0.5, 0.6, 0.8, 1) alloy is evaluated. Ribbons and 1 mm diameter ingots were prepared by melt-spinning technique and Cu-mold injection casting technique, respectively. The presence of the amorphous phase was confirmed through X-ray diffraction and high temperature differential scanning calorimetry (HT-DSC). Rapid solidification leads to fully amorphous ribbons for all compositions. Conversely, ingots with Co content with x > 0.5 present boride crystalline phases.Magnetization measurements were performed by means of vibration sample magnetometer in a temperature range from room temperature to 850 °C in order to determine the Curie temperature (TC) of the amorphous phase and to follow the formation of magnetic phases at high temperatures. In addition, hysteresis loops measurements were carried out to study the magnetic response of the samples. Co substitution until x = 0.5 is seen to simultaneously induce in the as cast ingots a decrease of coercive field from 52 to around 10 A/m and an increase of the Curie temperature of the amorphous phase from 480 to 700 K. A maximum saturation magnetization value of 123 emu/g was observed in the sample having x = 0.2. The role of Co substitution on glass formation is discussed on the basis of crystallization and melting behaviors, analyzed by HT-DSC. Magnetic properties are correlated with the presence of crystalline phases and their microstructures.

Glass formation and magnetic characterization of (Fe 78B 14Si 8)–Nb–Y alloys

In the present work, the glass formation of Fe 78B 14Si 8 alloy with small additions of Nb and Y has been investigated. Ribbons were prepared by planar-flow casting. Small ingots (up to 5 mm in diameter) were obtained by injection casting technique into a conical Cu mold. Thermal and structural properties were measured using differential scanning calorimetry (DSC) and X-ray diffraction (XRD), respectively. The microstructure has been observed by scanning electron microscopy (SEM). Quasi-static hysteresis loops have been measured using a vibrating sample magnetometer (VSM). Rapid solidification leads to a fully amorphous structure for all compositions. A partial amorphous structure has been obtained in samples prepared by copper mold casting, when adding Nb and Y. The role of Nb and Y addition on glass formation is discussed on the basis of melting behavior, analyzed by HT-DSC. Magnetic properties are correlated with the observed microstructures.

Phase transformations in rapidly solidified (Ti-Zr) 50(Ni-Cu-Sn) 50 alloys

Rapidly solidified samples of Ti 45Zr 5Ni 20Cu 25Sn 5 (at.%) alloy have been produced using the planar flow casting, twin roll casting and injection casting techniques. Depending on the cooling rate, different structural states are formed: amorphous, crystalline or mixed. The glass transition and crystallization behaviour of the amorphous phase as well as the martensitic transformation in the crystallized material have been studied by differential scanning calorimetry and X-ray diffraction. The effect of crystallization conditions and resulting microstructure on the martensitic transformation characteristics has been investigated.

Effect of the Be and Y on the martensite transformation parameters in TiNi compound

To our knowledge, the effect of Be and Y on the martensite transformation parameters in TiNi-based shape memory alloys was studied occasionally and mainly on a level of the technological additions. Recently, due to the development of non-conventio nal production technologies applied to the shape memory materials, both metals are found to be the appropriate canditates for production of the potential TiNi-based shape memory alloys in an initially amorphous structural state by means of the melt-spinning and injection casting techniques. First of all, the Be and Y attract attention due to satisfaction of the so-called golden rules known for the bulk amorphous alloy systems. We present the result of the experimental study regarding the systematic substitution of the main constituent elements Ti and Ni by Be and Y up to (2-10) at.%. In as-cast condition, all the Ti-Ni-Be and Ti-Ni-Y alloys undergo the dual B2 R B19' martensite transformation sequence, well resolved on the cooling run and often overlapping on the heating run. Both the TR and Ms transformatio n temperatures smoothly decrease with the Be or Y content, the slope to be higher for substitution of the Ti than the Ni. The ternary TiNiBe and TiNiY melt- spun ribbons produced in the standard technological condition are rather brittle and don't show a good metallic aspect. They are in the crystalline structural state and undergo the martensite transformation sequence similar to the bulk material but in the lower temperature range. The contribution of the chemical composition, microstructure and strain/stress field (caused by the difference in the atomic radii) to the martensite transformation temperatures is considered.

Precipitation of icosahedral phase from amorphous Zr65Cu17.5−xAl7.5Ni10Agx (x = 0, 5) alloys

Crystallization behavior of amorphous Zr65Cu17.5−xAl7.5Ni10Agx (x = 0, 5) alloys prepared by melt spinning and injection casting techniques has been studied using differential scanning calorimetry, x-ray diffractometry, and transmission electron microscopy. Ag addition changes crystallization sequence of the amorphous phase. The amorphous Zr65Cu17.5Al7.5Ni10 alloy crystallizes via simultaneous precipitation of icosahedral phase and NiZr2 phase in the first crystallization step whereas that in Zr65Cu12.5Al7.5Ni10Ag5 alloy crystallizes via precipitation of only icosahedral the phase. Partial replacement of Cu by Ag in Zr65Cu17.5Al7.5Ni10 alloy stabilized the icosahedral phase relative to competing intermetallic phases resulting in suppression of the precipitation of the NiZr2 phase, enhancement of the precipitation of icosahedral phase, and reduction of undercooled liquid range. Crystallization behavior of the amorphous Zr65Cu12.5Al7.5Ni10Ag5 alloy is not affected by cooling rate during solidification. Johnson–Mehl–Avrami analysis of isothermal transformation data suggests that the formation of the quasicrystalline phase is not entirely polymorphic in nature and may involve partitioning of the solute at later state.

Preparation of actinide metal targets using special casting techniques

Various casting techniques and mold design have been evaluated at Rocky Flats for preparing actinide metal targets. A tilt-pour casting technique is used for targets > 0.040 in. thick, and an injection casting technique has been developed for targets <0.040 in. thick. Plutonium, neptunium, and uranium metal ingots and disks ranging from 0.005–0.600 in. thickness have been cast.