Preparation of W–Al alloys by mechanical alloying

Tang, Huaguo; Ma, Xiaoteng; Zhao, Wei; Yan, Xiunan; Hong, Richang

doi:10.1016/s0925-8388(02)00760-0

Cited by 70 publications

(44 citation statements)

References 6 publications

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“…Because of the large differences in density and melting point between tungsten and aluminum, it is very difficult to synthesize this ternary carbide directly by tungsten, aluminum, and carbon elemental powders. In our previous paper, [14] we reported that a W 0.5 Al 0.5 alloy could be synthesized by mechanical alloying. Moreover, W 0.5 Al 0.5 has the same body-centered cubic structure as tungsten, and is stable at temperatures up to 1673 K. So it is possible for W 0.5 Al 0.5 to be carburized at high temperature to prepare the solid solution (W 0.5 Al 0.5 )C 1Àx as the reaction between tungsten and carbon to form WC.…”

Section: Introductionmentioning

confidence: 99%

“…Experimental Section W 0.5 Al 0.5 alloy was prepared by mechanical alloying of W/Al powders with an atomic ratio of 1:1 for about 20 h, as reported by Tang et al [14] The prepared W 0.5 Al 0.5 alloy (< 0.1 mm, 99 % purity) and carbon (< 34 mm, 99 % purity) were accurately weighed out, such that the W 0.5 Al 0.5 :C molar ratio was 1:(1Àx) + 0.02 (x = 0.00-0.50). The reason for the addition of a small excess of carbon is that a small amount of carbon should be oxidized and lost at the elevated temperature in the following steps.…”

Section: Introductionmentioning

confidence: 99%

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Crystal Structure and Carbon Vacancy Hardening of (W_0.5Al_0.5)C_1−x Prepared by a Solid‐State Reaction

Yan

Zhao

et al. 2005

ChemPhysChem

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Novel solid solutions of aluminum in tungsten carbide (WC) with or without carbon vacancies, which can be expressed by the chemical formula (W(0.5)Al(0.5))C(1-x) (x=0.0-0.5), have been synthesized by the solid-state reaction of W(0.5)Al(0.5) alloy and the proper amount of carbon at around 1673 K in vacuum. The reaction time decreases from 73 to 50 h on increasing the carbon vacancy concentration from 0 to 50 %. The formation of the intended products is certified, by X-ray diffraction, environmental scanning electron microscopy-energy-dispersive X-ray analysis, and inductively coupled plasma-atomic emission spectroscopy, even though the carbon vacancy concentration reaches the astonishing value of 50 %. The as-prepared (W(0.5)Al(0.5))C(1-x) samples have been identified as the hexagonal WC-type structure belonging to the space group P6m2 (Z=1). Moreover, the crystallographic results reveal that the substituting aluminum atoms in the WC are located in the 1a site (the W atom position of the WC structure) and the cell parameters decrease slightly with increasing vacancy concentration. The hardness of the (W(0.5)Al(0.5))C(1-x) system increases up to a maximum 2659 kg mm(-2) at a carbon vacancy concentration of about 35 %, and the density of (W(0.5)Al(0.5))C(1-x) is far lower than that of WC.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Crystal Structure and Carbon Vacancy Hardening of (W_0.5Al_0.5)C_1−x Prepared by a Solid‐State Reaction

Yan

Zhao

et al. 2005

ChemPhysChem

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“…Because of the very little mutual solid solubility (< 13 at.%) and the very large difference between the melting points of tungsten (3683 K) and aluminum (933 K), it is very difficult to prepare Al-W-C ternary system by melting or other equilibrium methods. In our previous paper, [9][10] we reported that (W 1-x Al x )C y (x=0.1 ∼ 0.86,y=0.5 ∼ 1.0) powder could be synthesized by mechanical alloying and solid state reaction. However, the mechanical properties of (W 1-x Al x )C y (x=0.1 ∼ 0.86,y=0.5 ∼ 1.0) have not been reported as a result of bulk alloys being not obtained.…”

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confidence: 99%

A Novel Cemented Hard Alloy Prepared by Mechanical Alloying and Hot‐Pressing Sintering

Qiao

Zhao

et al. 2007

Adv Eng Mater

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Owing to its exceptional hardness and superior wear resistance, tungsten carbide (WC) has a wide range of industrial applications, especially in the tool-cutting industry. [1] However, pure WC has many inherent shortcomings, such as room-temperature brittleness, high density and high operating costs. Therefore, in recent years, many studies have been focused on how to improve the physical and chemical properties of WC, as well as to reduce its high operating cost. In this sense, one first approach is partial substitution of WC by other nonoxide compounds, such as, Ti(C, N), MoC, Cr 2 C 3, and VC, [2][3][4] which results in a lower density while maintaining the high hardness and wear resistance. The second alternative is to modify the binder component, such as, Co, Fe, Ni etc, to improve the corrosion resistance and/or mechanical strength. [5][6][7][8] However, to date no work has been done on the solid solution of metals in WC. Aluminum is more ductile and lighter than tungsten, so dissolving aluminum into the lattice of WC to form a solid solution is expected to enhance the bend strength of WC and reduce its density. In addition, aluminum is inexpensive compared with tungsten, thus operating cost of ternary carbide Al-W-C are surely less than that of WC. Because of the very little mutual solid solubility (< 13 at.%) and the very large difference between the melting points of tungsten (3683 K) and aluminum (933 K), it is very difficult to prepare Al-W-C ternary system by melting or other equilibrium methods. In our previous paper, [9][10] we reported that (W 1-x Al x )C y (x=0.1 ∼ 0.86,y=0.5 ∼ 1.0) powder could be synthesized by mechanical alloying and solid state reaction. However, the mechanical properties of (W 1-x Al x )C y (x=0.1 ∼ 0.86,y=0.5 ∼ 1.0) have not been reported as a result of bulk alloys being not obtained. Because (W 1-x Al x )C y (x=0.1 ∼ 0.86,y=0.5 ∼ 1.0) has the same hexagonal structure as WC, [10] so we choose cobalt as the binder which is a good binder for WC sintering. One aim of this work is to fabricate the (W 0.5 Al 0.5 )C 0.5 -Co alloy bulk bodies. Hot-pressing (HP) as a common technique is a suitable and economical method to facilitate the sintering of (W 0.5 Al 0.5 )C 0.5 -Co hard alloy. Additionally, the mechanical properties and the microstructures of (W 0.5 Al 0.5 )C 0.5 -Co bulk bodies were tested. Figure 1 shows XRD pattern of (W 0.5 Al 0.5 )C 0.5 -13.3 %Co bulk alloy obtained at 1450°C and 40 MPa for 15 min. The peaks of of (W 0.5 Al 0.5 )C 0.5 phase are still stably and clearly. Table 1 shows the results of EDS analyses for the fracture of (W 0.5 Al 0.5 )C 0.5 -Co bulk specimens HP-ed with various cobalt contents. The results indicated that the bulk alloy specimens obtained by hot-pressing were identical with raw materials in composition and Al still dissolved in W after sintered at 1450°C by reason of finding no peaks of Al and/or aluminous compounds in XRD pattern, only a little oxygen and iron contaminate the of (W 0.5 Al 0.5 )C 0.5 -Co alloy during ball milling and hot-pres...

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“…[3] In this paper, we focus on fabricating in situ WAl 12 reinforced Al-based MMC via MA and HP using W 14 Al 86 alloy, which is of high microhardness, good oxidation resistance and low density, etc. [10] The mechanical properties and the microstructures of the MMC were also determined.Results and discussion. Synthesis of W 14 Al 86 alloy: The aluminum and tungsten powders were mixed to give a desired composition of W 14 Al 86 and mechanically milled for 10, 30, 50 and 70 h respectively in a stainless steel vial filled with argon.…”

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Processing, Microstructure and Mechanical Properties of in Situ Al‐based Metal Matrix Composite Reinforced with 22 wt%WAl₁₂ Particles

Cai

Tang

et al. 2006

Adv Eng Mater

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In the past decade, Al-based metal matrix composite (MMC) reinforced with particles has been received much attention due to its high elastic modulus, high strength and light weight that is of value to automobile and aerospace industries, etc. [1] Very recently, Yu et al [2] reported the structure and characterization of an in situ Al-based MMC reinforced with Al 2 O 3 and TiC produced by hot isostatic pressing (HIP) technique, which indicated that the mechanical performance of Al-10 wt%TiO 2 -1.5 wt%C is higher than that of Al-10 wt%TiO 2 due to formation of TiC and elimination of large intermetallic Al 3 Ti plates. By using a mechanical alloying technique, Jia et al [3] synthesized an Al 3 Ti particle and Nb flake reinforced Al matrix composite and found that the MA Al-12Ti-Nb has much more excellent mechanical properties and thermal stability than the MA Al-12Ti. Al-TiB 2 metal matrix composites prepared by exothermic reactions at 850°C using K 2 TiF 6 and KBF 4 salts and using stir cast route at above 1000°C, respectively, have also been documented by Lu's group. [4,5] Compared with these typical ceramic particulates, in situ intermetallic WAl 12 , fabricated by MA and vacuum hot pressing (HP) techniques, is a new reinforcement with clean grain boundary. However, synthesis of composites with in situ WAl 12 reinforcement has never been reported.Mechanical alloying is a solid-state powder processing technique which was effectively employed to prepare a variety of alloy powders or blend green samples, [6][7][8][9] The hotpressing technique is a highly evolved method of preparing full dense, good matrix-to-reinforcement compatible and microstructural homogeneous materials. Therefore, MMCs can be well synthesized by using the in situ technique. [3] In this paper, we focus on fabricating in situ WAl 12 reinforced Al-based MMC via MA and HP using W 14 Al 86 alloy, which is of high microhardness, good oxidation resistance and low density, etc. [10] The mechanical properties and the microstructures of the MMC were also determined.Results and discussion. Synthesis of W 14 Al 86 alloy: The aluminum and tungsten powders were mixed to give a desired composition of W 14 Al 86 and mechanically milled for 10, 30, 50 and 70 h respectively in a stainless steel vial filled with argon. Figure 1 shows a series of XRD patterns indicating the phase evolution as a function of milling time in the mixture. The as-received elemental blend showed the presence of both elemental aluminum and tungsten phases clearly. As milling time increased, intensity of Al peaks decreased continuously. After 70 h milling, Al peaks disappeared, whereas W peaks were still visible. It implied that Al completely dissolved in the remaining bcc W-based phase, indicating that W 14 Al 86 alloy was prepared by mechanical alloying process.Formation of in situ WAl 12 reinforcement: Figure 2 shows the typical XRD patterns of the HPed Al-15 wt%W 14 Al 86 samples under various sintering conditions. After sintering at 600 for 30 min ( Fig. 2(a)), the diffraction peaks ...

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Preparation of W–Al alloys by mechanical alloying

Cited by 70 publications

References 6 publications

Crystal Structure and Carbon Vacancy Hardening of (W_0.5Al_0.5)C_1−x Prepared by a Solid‐State Reaction

Crystal Structure and Carbon Vacancy Hardening of (W_0.5Al_0.5)C_1−x Prepared by a Solid‐State Reaction

A Novel Cemented Hard Alloy Prepared by Mechanical Alloying and Hot‐Pressing Sintering

Processing, Microstructure and Mechanical Properties of in Situ Al‐based Metal Matrix Composite Reinforced with 22 wt%WAl₁₂ Particles

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Preparation of W–Al alloys by mechanical alloying

Cited by 70 publications

References 6 publications

Crystal Structure and Carbon Vacancy Hardening of (W0.5Al0.5)C1−x Prepared by a Solid‐State Reaction

Crystal Structure and Carbon Vacancy Hardening of (W0.5Al0.5)C1−x Prepared by a Solid‐State Reaction

A Novel Cemented Hard Alloy Prepared by Mechanical Alloying and Hot‐Pressing Sintering

Processing, Microstructure and Mechanical Properties of in Situ Al‐based Metal Matrix Composite Reinforced with 22 wt%WAl12 Particles

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Crystal Structure and Carbon Vacancy Hardening of (W_0.5Al_0.5)C_1−x Prepared by a Solid‐State Reaction

Crystal Structure and Carbon Vacancy Hardening of (W_0.5Al_0.5)C_1−x Prepared by a Solid‐State Reaction

Processing, Microstructure and Mechanical Properties of in Situ Al‐based Metal Matrix Composite Reinforced with 22 wt%WAl₁₂ Particles