Full density consolidation of pure aluminium powders by cold hydro-mechanical pressing

Wei, Xianshun; Vekshin, B. S.; Крапошин, В. С.; Huang, Yue; Shen, Jun; Xia, Kenong

doi:10.1016/j.msea.2011.03.099

Cited by 11 publications

(4 citation statements)

References 29 publications

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“…The main positive aspect of ECAP in terms of properties enhancement is deriving (presumably) from the provided effect of cold welding between the powder particles [22][23][24]. Xia proves [22] that surface oxide layer can be fractured by SPD, leading also to exposure of fresh surfaces and spontaneous bonding between particles [23]. Lapovok [24] observes that this shear deformation would cause significant material flow, resulting in the significant closure of gaps between particles.…”

Section: Discussionmentioning

confidence: 99%

Microstructure, Fracture and Mechanical Properties of ECAPed Aluminum P/M Alloy with Respect to the Porosity

Bidulská

Bidulský

Grande

2014

MSF

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The main aim of this paper is to investigate the effects of different processing conditions on the behavior of a P/M (Powder Metallurgy) aluminum alloy with respect to the microstructure, fracture and mechanical properties. Moreover, the evolution of porosity as a consequence of pressing, sintering and ECAPing processes was investigated. A commercial Al-Mg-Si-Cu-Fe powder was used as material to be investigated. Different compacting pressures (400, 500, 600, 700 MPa) were applied. Specimens were dewaxed in a ventilated furnace at 400 °C for 60 min before sintering. Sintering was carried out in a vacuum furnace at 610 °C for 30 min. The specimens were ECAPed for 1 pass. The 2-dimensional quantitative image analysis was carried out by means of SEM and OM for the evaluation of the dimensional and morphological porosity characteristics. The detailed microstructure revealed the main features of sintering processes as well as secondary pores at the prior alloying particle sites. The tensile fracture surfaces in both studied processing condition (as-sintered and ECAP) show limited ductility, with fracture occurring on a plane normal to the tensile stress axis. Examination at higher magnifications revealed predominantly transparticle ductile features. In terms of mechanical properties, ECAP is almost doubling the tensile strength of the as-sintered materials

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Section: Discussionmentioning

confidence: 99%

Microstructure, Fracture and Mechanical Properties of ECAPed Aluminum P/M Alloy with Respect to the Porosity

Bidulská

Bidulský

Grande

2014

MSF

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“…They can also (positively) alter the residual stress state, reduce/eliminate possible presence of voids and porosity, etc. [15][16][17][18]. Moreover, the favorable combination of shear strain and compressive stress is advantageous for direct consolidation of powder-based workpieces [19].…”

Section: Introductionmentioning

confidence: 99%

Direct consolidation of an oxide dispersion strengthened alloy by hot rotary swaging

Kunčická,

Svoboda

2024

Materialwissenschaft Werkst

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Steels strengthened by alloying elements and precipitates typically maintain their enhanced properties up to the ferrite‐austenite transformation. However, oxide dispersion strengthened ferritic steels are creep resistant even at much higher temperatures given by dispersions of nanosized oxides. To ensure homogeneous dispersion of the oxides, powder metallurgy is used for preparation of the original material. The presented study investigates the effects of direct consolidation of powder of ferritic steel strengthened with yttrium oxide nanoparticles. The powders were mechanically alloyed and sealed into evacuated steel containers, which were subjected to gradual hot consolidation via the industrially applicable intensive plastic deformation method of rotary swaging. Investigations assessing the effects of several reduction ratios showed that the direct consolidation of the oxide dispersion strengthened steel was successful – in the macroscale – at the swaging ratio of 1.03; the quality of consolidation further increased with increasing swaging ratio. At the swaging ratio of 1.83, the consolidated bulk material featured ultra‐fine grains characterized with high angle grain boundaries, homogeneous dispersion of oxide precipitates, and the average Vickers microhardness of 706.6 HV 1.

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“…The CHMP consolidation process is largely dependent on the configuration of the axial compression stress and the radial hydrostatic pressure. As mentioned in previous investigations the gas atomized pure Al crystalline powders can be successfully consolidated into bulk material with full density and high performance at room temperature using CHMP [27]. It is vital to further study the consolidation process for amorphous or partially amorphous alloy powders by CHMP.…”

mentioning

confidence: 97%

“…Very recently, a cold hydromechanical pressing (CHMP) consolidation method that combines the triaxial compression principle and high pressure technology has been proposed [27]. The CHMP consolidation process is largely dependent on the configuration of the axial compression stress and the radial hydrostatic pressure.…”

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confidence: 99%

Bulk amorphous Al85Ni10Ce5 composite fabricated by cold hydro-mechanical pressing of partially amorphous powders

et al. 2011

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Gas atomized Al 85 Ni 10 Ce 5 partially amorphous alloy powders were successfully consolidated into bulk alloy specimens with high relative density at room temperature by cold hydromechanical pressing. The consolidated specimens have a high fracture strength of up to 1.1 GPa. Two densification mechanisms are proposed to explain the consolidation process. The viscous flow of the amorphous phase because of local heating facilities the elimination of residual pores. Over the last few decades Al-based amorphous alloys with high Al concentrations have received considerable attention because of their high strength combined with excellent bending ductility [1][2][3]. Although Al-based amorphous alloys exhibit remarkable mechanical properties compared to their crystalline counterparts, most of the as-quenched Al-based amorphous alloys can only be obtained by melt spinning in the shape of thin ribbons or by gas atomization in the form of powders. The glass forming ability (GFA) of Al-based amorphous alloys is relatively lower than that of other alloy systems. Only recently, Al-rich bulk metallic glasses with a diameter of 1 mm have been obtained by copper mould casting [4][5][6][7][8]. The size limitation has seriously restricted the practical application of Al-based amorphous alloys. The fabrication of bulk amorphous alloys by consolidating glassy powders has been shown to be an effective way to overcome the size limitation [9-12]. To consolidate amorphous alloy powders with a low GFA and thermal stability into bulk and full dense specimens without compromising their amorphous structure is a difficult task.The inhomogeneous deformation of an amorphous alloy at room temperature is mainly localized within a few shear bands leading to catastrophic failure. With an increase in temperature to the supercooled liquid region, which is defined by the temperature range between the glass transition temperature T g and the crystallization temperature T x , the amorphous alloy exhibits homogeneous deformation and viscous flow [13][14][15][16]. Consequently, the amorphous powders are always consolidated in the supercooled liquid region using their viscous flow characteristics by a conventional consolidation method such as vacuum hot pressing [17] and spark plasma sintering (SPS) [18]. Because of the relatively low crystallization temperature of Al-based amorphous alloys, exposure at high temperature usually leads to crystallization. On the other hand, high temperature is necessary to obtain tight powder particle bonding. However, the temperature fluctuation and temperature gradient, which are difficult to control precisely in a conventional consolidation process, may cause crystallization and deteriorate the material's properties [19][20][21]. To reduce the influence of temperature control precision, amorphous alloys with a wide supercooled liquid region are always used as

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Full density consolidation of pure aluminium powders by cold hydro-mechanical pressing

Cited by 11 publications

References 29 publications

Microstructure, Fracture and Mechanical Properties of ECAPed Aluminum P/M Alloy with Respect to the Porosity

Microstructure, Fracture and Mechanical Properties of ECAPed Aluminum P/M Alloy with Respect to the Porosity

Direct consolidation of an oxide dispersion strengthened alloy by hot rotary swaging

Bulk amorphous Al85Ni10Ce5 composite fabricated by cold hydro-mechanical pressing of partially amorphous powders

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