Metal solid freeform fabrication using semi-solid slurries

Rice, Christopher S.; Méndez, Patricio F.; Brown, Stuart B.

doi:10.1007/s11837-000-0065-5

Cited by 26 publications

(9 citation statements)

References 5 publications

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“…In addition, there is the possibility of using semi-solid slurries in Solid FreeForm (SSF) technology [44]. This method deposits a stream of slurry through a nozzle that moves relative to a substrate.…”

Section: Types Of Semi-solid Processingmentioning

confidence: 99%

Modelling the semisolid processing of metallic alloys

Atkinson

2005

Progress in Materials Science

518

160

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Semi-solid processing of metallic alloys and composites utilises the thixotropic behaviour of materials with non-dendritic microstructure in the semi-solid state. The family of innovative manufacturing methods based on this behaviour has been developing over the last twenty years or so and originates from scientific work at MIT in the early 1970s. Here, a summary is given of:-routes to spheroidal microstructures; types of semi-solid processing; and advantages and disadvantages of these routes.Background rheology and mathematical theories of thixotropy are then covered as precursors to the main focus of the review on transient behaviour of semi-solid alloy slurries and computational modelling. Computational Fluid Dynamics (CFD) can be used to predict die filling. However, some of the reported work has been based on rheological data obtained in steady state experiments, where the semi-solid material has been maintained at a particular shear rate for some time. In reality, in thixoforming, the slurry undergoes a sudden increase in shear rate from rest to 100s -1 or more as it enters the die. This change takes place in less than a second. Hence, measuring the transient rheological response under rapid changes in shear rate is critical to the development of modelling of die filling and successful die design for industrial processing. The modelling can be categorised as one phase or two phase and as finite difference or finite element. Recent work by Alexandrou and co-workers and, separately Modigell and co-workers, has led to the production of maps which, respectively summarise regions of stable/unstable flow and regions of laminar/transient/turbulent fill. These maps are of great potential use for the prediction of appropriate process parameters and avoidance of defects. A novel approach to modelling by Rouff and coworkers involves micro-modelling of the 'active zone' around spheroidal particles.There is little quantitative data on the discrepancies or otherwise between die fill simulations and experimental results (usually obtained through interrupted filling).There are no direct comparisons of the capabilities of various software packages to model the filling of particular geometries accurately. In addition, the modelling depends on rheological data and this is sparse, particularly for the increasingly complex two-phase models. Direct flow visualisation can provide useful insight and avoid the effects of inertia in interrupted filling experiments.

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Section: Types Of Semi-solid Processingmentioning

confidence: 99%

Modelling the semisolid processing of metallic alloys

Atkinson

2005

Progress in Materials Science

518

160

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“…Semisolid free forming was developed as a rapid prototyping technique to produce metal parts in the early to mid-1990s (102,103). The method involves preparing slurry under mechanical stirring and extruding the slurry and depositing on a moving table to build the part.…”

Section: Semisolid Free Forming Technologymentioning

confidence: 99%

Semisolid Processes

Govender

Möller

Damm

2014

Comprehensive Materials Processing

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“…However, the majority of metal-related work in the field of AM employs costly lasers or electron beam sources [5], which necessitate advanced and expensive AM methods to produce the final product. Employing semisolid metal (SSM) processing with the AM metal-base will address many of these challenges, offer greater advantages to the manufacturing process [6] and would achieve an efficient, affordable and widely accessible metallic AM process.…”

Section: Introductionmentioning

confidence: 99%

“…SSM was discovered around fifty years ago by Spencer at the Massachusetts Institute of Technology (MIT) while he was investigating the hot tearing of steels during solidification [7]. SSM is a method for metal forming that is exploited commercially using non-ferrous [5][6][7][8] and ferrous [9][10][11][12] metals like magnesium, aluminum alloys, copper, steel and cast iron. SSM is equally applicable to any alloy with a sufficient melting range process window.…”

Section: Introductionmentioning

confidence: 99%