Nanostructure development in refractory metals: ECAP processing of Niobium and Tantalum using indirect-extrusion technique

A modified ECAP die by implementing the principles of indirect extrusion was fabricated to process refractory metals of Niobium and Tantalum. The main advantage of this modified technique over conventional method of ECAP is the reduction of frictional force during extrusion. Finite Element Method wa...

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Bibliographic Details
Published in:International journal of refractory metals & hard materials 2019-02, Vol.79, p.1-9
Main Authors: Omranpour, Babak, Kommel, Lembit, Mikli, Valdek, Garcia, Edgar, Huot, Jacques
Format: Article
Language:English
Subjects:
Backward extrusion
Extrusion dies
Finite element method
Grain refinement
Hardness
Indirect-extrusion ECAP
Mechanical properties
Nanostructured metals
Niobium
Refractory materials
Refractory metals
Tantalum
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Summary:A modified ECAP die by implementing the principles of indirect extrusion was fabricated to process refractory metals of Niobium and Tantalum. The main advantage of this modified technique over conventional method of ECAP is the reduction of frictional force during extrusion. Finite Element Method was utilized to demonstrate the difference between the extruding loads during the process. Several samples of Niobium and Tantalum were subjected to ECAP in different passes. Analysis of experimental results demonstrated a dramatic improvement in mechanical properties. Similarly, microstructure and XRD analyses of the samples showed noticeable enhancement in grain refinement of metals towards nanoscale. [Display omitted] •A modified ECAP die was manufactured and utilized for processing of refractory metals.•Niobium and Tantalum were processed using this die at room temperature.•Results of FEM simulations showed considerable reduction in friction and extruding load.•This process led to an improvement in hardness and microstructure development in metals.
ISSN:0263-4368
2213-3917
DOI:10.1016/j.ijrmhm.2018.10.018