Suction-cast Alloy Research Articles

Self-propagating high-temperature synthesis of AlxCoCrFeNiMoy high-entropy alloys: thermochemical modelling, microstructural evaluation and high temperature oxidation behaviour

In this study, the feasibility of the synthesis of AlxCoCrFeNiMoy (0.5 < x < 3, y = 0.5,1) alloys via cost and energy efficient thermochemical modelling assisted (FactSage™) aluminothermic self-propagating high-temperature synthesis (SHS) method was investigated. In addition, selected SHS alloys were also suction-casted into a bar shape by using a vacuum arc melter and the microstructural changes and oxidation behaviour of selected alloys were investigated. The characterization results demonstrated that AlxCoCrFeNiMoy (0.5 < x < 3, y = 0.5,1) master alloys can be successfully synthesized via thermochemical modelling assisted SHS method with a substantial composition control. The microstructures of the SHS alloys were found to comprise of the FCC-A1, BCC (A2, B2) and σ phases with varying fractions depending on the composition. Increasing Al content was found to increase the hardness of the alloys from 278 HV to 829 HV for the AlxCoCrFeNiMo0.5 system. For AlxCoCrFeNiMo system, on the other hand, it had an increasing effect from Al0.5 to Al1.0 (from 659 HV to 903 HV) initially and then decreased the hardness to the levels of 773 HV with the further addition of Al. Suction-cast alloys exhibited rather similar microstructures with similar phase constituents and hardness values. As a general trend primer B2 phase fraction was increased due to higher cooling rate. Oxidation studies revealed that the Al3.0Mo0.5 alloy, which has higher B2 content (919 HV), exhibited better oxidation resistance after 100 h of exposure to air at 800 °C. Postulated scaling mechanisms, supported with the CALPHAD simulations and Raman analyses, revealed the formation of non-protective spinel oxides and sublimation of volatile MoOx oxides before the stabilization of a protective M2O3 (M = Al,Cr) layer, especially for the AlCoCrFeNiMo alloy.

Cooling rate evaluation during solidification in the suction casting process

In this work, axial cooling rates during solidification in the Fe-25Ni (wt.%) suction-cast alloy were evaluated based on cellular spacing measurements. Good agreement of the experimental results with the 20/{d(cm)}2 relationship was observed for the standard water-cooling system temperature of 17 ± 1 °C. The importance of this casting parameter is reported for the first time. A linear decrease in the cooling rate with increasing water-cooling system temperature is demonstrated and at least 20% lower values are expected for a temperature increase by 10 °C compared to standard conditions. Furthermore, the cooling rate exponentially decreases with increasing rod diameter for all water-cooling system temperatures. A new expression for cooling rates during solidification, taking into account the casting parameter (WCST expressed in K), i.e. CR=10-0.0059⋅WCST+4.9746{d(mm)}0.0195⋅WCST-3.6351 , is proposed. The reliability and benefits of this formula have been demonstrated by casting the Zr50Cu40Al10 glass-forming alloy at various water-cooling system temperatures.

A comparative analysis of Inconel 718 made by additive manufacturing and suction casting: Microstructure evolution in homogenization

Homogenization is one of the critical stages in the post-heat treatment of additive manufacturing (AM) component to achieve uniform microstructure. During homogenization, grain coarsening could be an issue to reserve strength, which requires careful design of both time and temperature. Therefore, a proper design of homogenization becomes particularly important for AM design, for which work hardening is usually no longer an option. In this work, we discovered an intriguing phenomenon during homogenization of suction-cast and AM Inconel 718 superalloys. Through both short and long-term isothermal heat treatments at 1180 °C, we observed an abnormal grain growth in the suction-cast alloy but continuous recrystallization in the alloy made by laser powder bed fusion (LPBF). The grain size of AM samples keeps as small as 130 μm and is even slightly reduced after homogenization for 12 h. The homogeneity of Nb in the AM alloys is identified as the critical factor for NbC formation, which further influences the recrystallization kinetics at 1180 °C. Multi-type dislocation behaviors are studied to elucidate the grain refinement observed in homogenized alloys after LPBF. This work provides a new pathway on microstructure engineering of AM alloys for improved mechanical performance superior to traditionally manufactured ones.

Microstructure and mechanical properties of annealed, quenched and suction cast Ti-6Al-4V

The effect of heat treatment or processing method on microstructure, mechanical properties and phase formation in Ti-6Al-4V alloys has been researched. The alloys in as-delivered, annealed, quenched and suction cast conditions were investigated using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and synchrotron X-ray diffraction (SXRD) analysis. The different processing- or heat treatment routes lead to significant changes in the phase composition. The quenched and suction cast alloys exhibited a mixture of martensitic α′ / α″ and BCC β phase. In annealed and as-delivered alloys α′ + β phase mixtures was detected. The properties of alloys strongly depend on heat treatment and / or processing route.

Glass forming ability of the Zr50Cu40Al10 alloy with two oxygen levels

The effect of oxygen content on the glass forming ability of the Zr50Cu40Al10 alloy is presented. Two different oxygen levels, 194 ± 26 wt. ppm and 918 ± 72 wt. ppm, in the arc melted and suction cast alloys were obtained using Zr metal of different forms and nominal oxygen contents. Critical diameters for glass formation were determined by microstructural observations of cast conical and rod-shaped samples. Their structures were further investigated by X-ray diffraction. The critical diameter of the alloy with the lower oxygen content was 8 mm, while for the higher oxygen content it was below 3 mm. For the latter, the τ3 (Zr51Cu28Al21) crystalline inclusions were observed in the central part of the 3 mm diameter sample. The fully amorphous samples exhibited a large supercooled liquid range and a high reduced glass transition temperature.

Enhancement of High Temperature Strength of 2219 Alloys Through Small Additions of Nb and Zr and a Novel Heat Treatment

This paper presents a detailed investigation on the effect of small amount of Nb and Zr additions to 2219 Al alloy coupled with a novel three-stage heat treatment process. The main aim of the work is to increase the high temperature strength of 2219 alloy by introducing thermally stable L12 type ordered precipitates in the matrix as well as by reducing the coarsening of metastable strengthening θ″ and θ′ precipitates. To achieve this, small amounts of Nb and Zr are added to 2219 alloy melt and retained in solid solution by suction casting in a water-cooled copper mould having a cooling rate of 102 to 103 K/s. The suction cast alloy is directly aged at 673 K (400 °C) to form L12 type ordered coherent Al3Zr precipitates. Subsequently, the alloy is solution treated at 808 K (535 °C) for 30 minutes to get supersaturation of Cu in the matrix without significantly affecting the Al3Zr precipitates. Finally, the alloy is aged at 473 K (200 °C), which results in the precipitation of θ″ and θ′. Microstructural characterization reveals that θ″ and θ′ are heterogeneously precipitated on pre-existing uniformly distributed Al3Zr precipitates, which leads to a higher number density of these precipitates. This results in a significant increase in strength at room temperature as well as at 473 K (200 °C) as compared to the 2219 alloy. Furthermore, the alloy remains thermally stable after prolonged exposure at 473 K (200 °C), which is attributed to the elastic strain energy minimization by the conjoint Al3Zr/θ′ or Al3Zr/θ″ precipitates, and the high Zr and Nb solute-vacancy binding energy, retarding the growth and coarsening of θ″ and θ′ precipitates.

Structural Stability of the Metastable β-[(Mo0.5Sn0.5)-(Ti13Zr1)]Nb1 Alloy with Low Young’s Modulus at Different States

β-Ti alloys with low Young’s modulus are always formed at the lower critical limit of β stabilization, where the β structure is prone to be destabilized. This present work aims at studying the structural stability of β-Ti alloy [(Mo0.5Sn0.5)-(Ti13Zr1)]Nb1 with low Young’s modulus (E) at different states of suction-cast (SC) and solution-treated (ST), and the deformation mechanisms of this alloy are also discussed. The solution treatment eliminates the composition heterogeneity of the SC alloy, and no second phases are precipitated from the β matrix, as a result of a further decrease of E from 48 GPa (SC) to 43 GPa (ST). After tension deformation, the stress-induced {112} $$ \langle 111\rangle $$ β twinning is dominant in the SC alloy, while the stress-induced phase transformation of β → α″ plays a decisive role in the ST alloy, which results from the different structural stabilities of β matrix at different states. The minor second-phase precipitation renders the matrix with a slightly higher β stability of the SC alloy than that of the ST one.

Solidification Behavior in Newly Designed Ni-Rich Ni-Ti-Based Alloys

The present investigation reports phase and microstructure evolution during solidification of novel Ni-rich Ni-Ti-based alloys, Ni60Ti40, Ni50Cu10Ti40, Ni48Cu10Co2Ti40, and Ni48Cu10Co2Ti38Ta2 during suction casting. The design philosophy of the multicomponent alloys involves judicious selection of alloying elements such as Cu, Co, and Ta in the near Ni60Ti40 eutectic alloy by replacing both Ni and Ti so that phase mixture in the microstructure remains the same from the binary to quinary alloy. The basic objective is to study the effect of addition of Cu, Co, and Ta on the phase evolution and transformation in the Ni-rich Ni-Ti-based alloys. The detailed electron microscopic studies on these suction cast alloys reveal the presence of ultrafine eutectic lamellae between NiTi and Ni3Ti phases along with dendritic NiTi and Ti2Ni phases. It has also been observed that in the binary (Ni60Ti40) alloy, the ordered NiTi (B2) phase transforms to trigonal (R) phase followed by NiTi martensitic phase (M-phase), i.e., B2 → R-phase → M-phase during solid-state cooling. However, the addition of alloying elements such as Cu, Co to the binary (Ni60Ti40) alloy suppresses the martensitic transformation of the ordered NiTi (B2) dendrite. Thus, in the ternary and quaternary alloys, the ordered NiTi (B2) phase is transformed to only trigonal (R) phase, i.e., B2 → R-phase. The secondary precipitate of Ti2Ni has been observed in all of the studied alloys. Interestingly, Ni48Cu10Co2Ti38Ta2 quinary alloy shows the disordered nature of NiTi dendrites. The experimentally observed solidification path is in good agreement with Gulliver–Scheil simulated path for binary alloy, whereas simulated solidification path deviates from the experimental results in case of ternary, quaternary, and quinary alloys.

Development in corrosion resistance by microstructural refinement in Zr-16 SS 304 alloy using suction casting technique

Zirconium (Zr)-stainless steel (SS) hybrid alloys are being considered as baseline alloys for developing metallic-waste-form (MWF) with the motivation of disposing of Zr and SS base nuclear metallic wastes. Zr–16wt.% SS, a MWF alloy optimized from previous studies, exhibit significant grain refinement and changes in phase assemblages (soft phase: Zr2(Fe, Cr)/α-Zr vs. hard phase: Zr3(Fe, Ni)) when prepared by suction casting (SC) technique in comparison to arc-cast-melt (AMC) route. Variation in Cr-distribution among different phases are found to be low in suction cast alloy, which along with grain refinement restricted Cr-depletion at the Zr2(Fe, Cr)/Zr interfaces, prone to localized attack. Hence, SC alloy, compared to AMC alloy, showed lower current density, higher potential at the breakdown of passivity and higher corrosion potential during polarization experiments (carried out under possible geological repository environments, viz., pH 8, 5 and 1) indicating its superior corrosion resistance.

Microstructural refinement and enhanced mechanical properties of suction-cast NiTi-Al alloy for structural use

A significant refinement of the microstructure of structural NiTi alloy was achieved through a combination of Al addition and fabrication by suction casting. This is attributed to the change from a layer-by-layer to volume solidification mode with Al content increasing, which causes a change in grain shape from columnar to equiaxed. Furthermore, when compared with conventional casting, suction casting optimizes the microstructure of the alloy by refining the grain size and ensuring a homogeneous distribution of Ti2Ni and Ni2TiAl phases. The high cooling rate of suction casting also delays the formation of β′-Ni2TiAl phase. Finally, this fine microstructure and uniform distribution of intermetallic phases result in the ultimate compressive strength of up to 2463.7 MPa, representing an improvement of 370 MPa over conventionally cast NiTi-Al alloy.

Novel BCC Anode Materials for High-Power Alkaline MH-Air Batteries

Aqueous metal hydride air batteries (MH-Air) offer an inexpensive and safe alternative to the Li-ion batteries for electric vehicles. To be competitive with Li-ion batteries, the energy density of a metal hydride battery system can be improved by introducing a low-mass bifunctional air cathode and developing a higher capacity anode material. V-based BCC alloys are promising high-capacity anode materials, and discharge capacities of greater than 450 mAh/g have been reported for TiV2.1-xCrxNi0.3 alloys.1 V-based BCC alloys containing Ti and Ni have been shown to separate chemically into a two-phase mixture with a minority Ni-Ti phase within a V-rich matrix,2 and we report the effects of this unmixing on electrochemical properties. The Ti-V-Cr-Ni BCC electrode materials were prepared by arc melting and rapid cooling with an Edmund Buhler compact MAM-1 with an attached suction casting crucible. The control samples were made by conventional arc melting under Ar. As-cast ingots were pulverized by hydriding in a Sievert’s apparatus. The samples were analyzed by x-ray diffractometry (XRD), scanning and transmission electron microscopy (SEM, TEM) and energy-dispersive x-ray spectrometry (EDS). The anode was prepared by pressing a mixture of alloy and Ni powders onto Ni mesh. Electrochemical cycling experiments were conducted in a half cell containing 30% aqueous KOH electrolyte, a Ni(OH)2 counter electrode and an Hg/HgO reference electrode. The electrode was charged at 100mA/g and discharged three times at 167mA/g, 50mA/g, and 10mA/g; each to a cut-off voltage of -0.7V vs. Hg/HgO. EDS mapping showed, as expected,2 a Ti-Ni rich secondary phase in the arc melted sample that permeates the micron-scale primary V phase. (Fig. 1, top, Ni phase in green.) No phase segregation is resolved by EDS for the suction cast alloy. (Fig. 1, bottom). For the first 100 charge-discharge cycles, both materials gave similar capacities. However, at each cycle, the suction cast alloy consistently discharges with 20%-40% more capacity during the high-rate step (167mA/g, ~C/3, 1st step in Fig. 2). It has been argued that the Ni-Ti phase is important for the electrocatalytic dissociation of H2 molecules during charge, and the matrix V-rich phase is the storage region for hydrogen.2 Reducing the length scale of the phase segregation of the Ni-Ti regions by rapid cooling may therefore improve the kinetics of the material by reducing the hydrogen diffusion length and by increasing surface area for electrocatalysis. Inoue, et al. Electrochimica Acta, (2012), 59, 23-31.Tsukahara, et al., J. Alloys Comp. (1997), 253-4, 583-6. Figure 1

Study on the Microstructure and Oxidation Properties of near Eutectic Nb-Si Alloys

In this paper, we report a significant improvement in Microstructure and oxidation roperties of near eutectic NbSi alloys by the addition of aluminum (Al) and control of microstructural length scale. A comparative study of two alloys Nb-18.79at%Si and Nb-12.3at%Si-9at%Al were carried out. The processing for microstructure refinements were carried out by vacuum suction casting in water cooled thick copper mould. It is shown that addition of Al suppresses Nb3Si phase and promotes βNb5Si3phase under nonequilibrium solidification condition. The microstructural length scale and in particular eutectic spacing reduces significantly to 50100 nm in suction cast ternary alloy. The indentation fracture toughness of Al containing suction cast alloy shows a value of 20.2±0.5 MPam which represents a major improvement over bulk NbSi eutectic alloy. The detailed thermal studies confirm a multifold improvement in oxidation resistance up to 1000°C.

Microstructure and storage properties of low V-containing Ti–Cr–V hydrogen storage alloys prepared by arc melting and suction casting

The microstructure and hydrogen storage properties of low V content (Ti0.46Cr0.54)100−xVx (x = 2.5–7.1, at%) and (TiyCr1−y)95V5 (y = 0.38–0.54) alloys were investigated. These alloys were prepared by arc melting and copper mould suction casting. The structures of as-cast (Ti0.46Cr0.54)100−xVx (x = 2.5, 5.0, and 7.1) alloy ingots evolve with V contents from pure Laves- (x = 2.5) to dual-phase TiCr2-BCC structures (5.0 and 7.1), whereas the suction-cast (Ti0.46Cr0.54)100−xVx (x = 2.5, 5.0, and 7.1) alloys only contain single BCC phase. The suction-cast alloy rod (Ti0.46Cr0.54)95V5, containing only 5.0 at% V is shown to possess the optimum hydrogen absorption capacity, with the maximum hydrogen content of 3.14 wt%. Furthermore, the hydrogen storage properties of the suction-cast low V alloys (TiyCr1−y)95V5 (y = 0.38–0.54) are sensitive to Ti/Cr ratios and only those alloys with Ti/Cr ratios close to the CN14 cluster [Ti7Cr8] have good hydrogen storage properties.

A Significant Improvement in Mechanical Properties of near Eutectic Nb-Si Alloys

In this paper, a significant improvement in mechanical and oxidation properties of near eutectic Nb–Si alloys by the addition of aluminum (Al) and control of microstructural length scale were studied. A comparative study of two alloys Nb-18.79at%Si and Nb-12.3at%Si-9at%Al were carried out. Compression test yields the ultimate strength of 1.8±0.1 GPa and engineering strain of 2.3±0.03%. In comparison, the binary Nb-18.79 at% Si alloy possesses an ultimate strength of 1.35±0.1 GPa and strain of 0.2±0.01% when processed under identical conditions. The indentation fracture toughness of Al containing suction cast alloy shows a value of 20.2±0.5 MPa which represents a major improvement over bulk Nb–Si eutectic alloy

Effects of Phosphorus and Carbon Contents on Amorphous Forming Ability in Fe-based Amorphous Alloys Used for Thermal Spray Coatings

Cost-effective Fe-based amorphous alloys used for thermal spray coatings were developed by varying contents of P and C, and their microstructure, hardness, and corrosion resistance were analyzed. In order to achieve chemical compositions having high amorphous forming ability, thermodynamically calculated phase diagrams of Fe-Al-P-C-B five-component system were used, from which compositions of super-cooled liquid having the lowest driving force of formation of crystalline phases were obtained. The thermodynamic calculation results showed that only phases of Fe3P and Fe3C were formed in the Fe78Al2P(18.3−x)C x B1.7 alloy system. Considering driving force curves of Fe3P and Fe3C, the carbon contents were selected to be 6.90 and 7.47 at. pct, when the thermodynamic calculation temperatures were 697 K (414 °C) and 715 K (442 °C), respectively. According to the microstructural analysis of suction-cast alloys, the Fe78Al2P10.83C7.47B1.7 alloy showed a fully amorphous microstructure, whereas the Fe78Al2P11.40C6.9B1.7 and Fe78Al2P10.3C8.0B1.7 alloys contained Fe3P and Fe3C phases. This Fe78Al2P10.83C7.47B1.7 alloy showed the better hardness and corrosion resistance than those of conventional thermal spray coating alloys, and its production cost could be lowered using cheaper alloying elements, thereby leading to the practical application to amorphous thermal spray coatings.

Electron Microscopic Study on the Suction Cast In Situ Ti-Fe-Sn Ultrafine Composites

The current investigation reports detailed study on the microstructural evolution in the suction cast hypereutectic Ti71Fe29−x Sn x alloys during Sn addition with x = 0, 2, 2.5, 3, 3.85, 4.5, 6, and 10 at. pct and the solidification of these ternary alloys using SEM and TEM. These alloys have been prepared by melting high-purity elements using vacuum arc melting furnace under high-purity argon atmosphere. This was followed by suction casting these alloys in the water-cooled split Cu molds of diameters, ϕ = 1 and 3 mm, under argon atmosphere. The results indicate the formation of binary eutectic between bcc solid solution β-Ti and B2 FeTi in all alloys. β-Ti undergoes eutectoid transformation, β-Ti → α-Ti + FeTi, during subsequent solid-state cooling, leading to formation of hcp α-Ti and FeTi. For alloys x < 2, the primary FeTi forms from the liquid before the formation of eutectic with minute scale Ti3Sn phase. For alloys with 2 ≥ x ≤ 10, the liquid is found to undergo ternary quasi-peritectic reaction with primary Ti3Sn, L+Ti3Sn → β-Ti+FeTi, leading to formation of another kind of FeTi. In all the other alloy compositions (3.85 ≥ x ≤ 10), Ti3Sn and FeTi dendrites are observed in the suction cast alloys with profuse amount of Ti3Sn being formed for alloys with x ≥ 4.5. The current study conclusively proves that the liquid undergoes ternary quasi-peritectic reaction involving four phases, L + Ti3Sn → β-Ti + FeTi, which lies at the invariant point Ti69.2±0.8Fe27.4±0.7Sn3.4±0.2 (denoted by P). Below P, there is one univariant reaction, i.e., L → β-Ti + FeTi for all alloy compositions, whereas above P, liquid undergoes one of the univariant reactions, i.e., L + β-Ti → Ti3Sn (Sn = 2, 2.5, 3, and 4.5 at. pct) or L + FeTi → Ti3Sn for alloys (Sn = 6, 10 at. pct). For alloy with Sn = 3.85 at. pct, the ternary quasi-peritectic reaction is co-operated by two monovariant eutectic reactions, i.e., L → β-Ti + FeTi below P and L → FeTi + Ti3Sn above P. Detailed microstructural information allows us to construct liquidus projection of the investigated alloys. The results are critically discussed in the light of available literature data.

Microstructure and mechanical properties of oxidation resistant suction cast Nb–Si–Al alloy

In this paper, we report a significant improvement in mechanical and oxidation properties of near eutectic Nb–Si alloys by the addition of aluminum (Al) and control of microstructural length scale. A comparative study of two alloys Nb-18.79at%Si and Nb-12.3at%Si-9at%Al were carried out. The processing for microstructure refinements were carried out by vacuum suction casting in water cooled thick copper mould. It is shown that addition of Al suppresses Nb3Si phase and promotes βNb5Si3 phase under nonequilibrium solidification condition. The microstructural length scale and in particular eutectic spacing reduces significantly to 50–100nm in suction cast ternary alloy. A detailed TEM study shows the presence of δ-Nb11Si4 phase in Nb matrix. The hardness of Nb solid solution can be increased as a consequence to a level observed in Nb3Si intermetallic due to the well oriented precipitates. Compression test yields the ultimate strength of 1.8±0.1GPa and engineering strain of 2.3±0.03%. In comparison, the binary Nb-18.79at% Si alloy possesses an ultimate strength of 1.35±0.1GPa and strain of 0.2±0.01% when processed under identical conditions. The latter exhibits coarser microstructural length scale (300–400nm) and a brittle behavior. The indentation fracture toughness of Al containing suction cast alloy shows a value of 20.2±0.5MPa√m which represents a major improvement over bulk Nb–Si eutectic alloy. The detailed thermal studies confirm a multifold improvement in oxidation resistance up to 1000°C.

Effect of Gallium on microstructure and mechanical properties of Nb–Si eutectic alloy

In this paper, we report a significant improvement in mechanical properties of near eutectic Nb–Si alloys by addition of Gallium (Ga) and control of microstructural length scale. A comparative study of two alloys Nb-18.79 at.%Si and Nb-20.2 at.%Si–2.7 at.%Ga were carried out. The microstructure refinements were carried out by vacuum suction casting in water cooled thick copper mold. It is shown that addition of Ga suppresses Nb3Si phase and promotes β-Nb5Si3 phase. The microstructural length scale and in particular eutectic spacing reduces significantly to 50–100 nm in suction cast ternary alloys. Compression test shows a strength of 2.8 ± 0.1 GPa and plasticity of 4.3 ± 0.03%. In comparison, the binary Nb-18.79 at.%Si alloy processed under identical conditions exhibit coarser length scale (300–400 nm) and brittle behavior. The fracture toughness of Ga containing suction cast alloy shows a value of 24.11 ± 0.5 MPa√m representing a major improvement for bulk Nb–Si eutectic alloy.

CLUSTER--PLUS--GLUE--ATOM MODEL AND COMPOSITION DESIGN OF BCC Ti--Mo--Nb--Zr SOLID SOLUTION ALLOYS WITH LOW YOUNG'S MODULUS

利用＂团簇＋连接原子＂结构模型研究了典型低弹bccβ-Ti固溶体合金的成分特征.对现有低弹β-Ti固溶体合金的成分分析表明它们均满足团簇式[CN14团簇]（连接原子）x.根据该式,设计了Ti-Mo-Nb-Zr系列合金[MoTi（14）]Ti（质量分数表达时为Ti-11.8Mo）,[MoTi（14）]Nb（Ti-11.2Mo-10.8Nb）,[MoTi（14）]Nb2（Ti-10.1Mo-19.5Nb）和[Mo（Ti（13）Zr）]Nb2（Ti-9.2Zr-9.6Mo-18.7Nb）,并采用Cu模吸铸快冷技术制备直径为3和6 mm的合金棒.结果表明,吸铸制备的合金均为bcc结构;当连接原子由Ti变成更低弹的Nb时,合金弹性模量降低;低弹Zr替代Ti进一步降低了合金的弹性模量,[Mo（Ti（13）Zr）]Nb2合金的弹性模量E=72 GPa.铸态样品经过固溶和水淬处理后弹性模量降低.

Microstructure and compressive properties of NiAl–Cr(Mo)–Dy near eutectic alloy prepared by suction casting

The NiAl–Cr(Mo) eutectic alloy doped with Dy was prepared by suction casting technique and its microstructure and mechanical properties were investigated. It is found that with the addition of Dy, the Ni5Dy phase is formed along the NiAl/Cr(Mo) phase boundary in the intercellular region. By the suction casting method, the microstructure of the alloy get well optimisation which can be characterised by the fine interlamellar spacing, high proportion of eutectic cell area and fine homogeneous distributed Ni5Dy phase. The compression test results reveal that the room temperature and high temperature mechanical properties of the suction cast alloy improve significantly, compared with the conventionally cast alloy.