Insight into single-fiber push-out test of tungsten fiber-reinforced tungsten

Abstract

To overcome the intrinsic brittleness of tungsten (W), a tungsten fiber-reinforced tungsten-composite material (W f /W) is a possible solution. The introduction of energy dissipation mechanisms like fiber bridging or fiber pull-out by means of an engineered interface between fiber and matrix mitigate the brittleness of tungsten and lead to a pseudo-ductile material behaviour. The push-out test of single-fiber samples is an experimental method to investigate the properties of the interface between fiber and matrix of composite materials. It is widely used for the investigation of ceramic composites. This method was also used to investigate the debonding and frictional properties of the Er2O3 interface region between fiber and matrix of W f /W single-fiber samples made by CVD-and HIP-processes. In this article finite element calculations are used to get a better understanding of the processes acting in the interface during a push-out test of W f /W. A detailed overview of the debonding progress and of the corresponding stress states of the interface during the different stages of the test is presented. In addition the sensitivity of the push-out behaviour regarding the different interface properties and the plastic flow curve of the tungsten fiber are investigated.

Fusion Materials Development at Forschungszentrum Jülich

“…[104,116] Studies to understand the pull-out of fibers include modeling. [130] For the developed PM production of W f /W, the homogenous introduction of powder between the fibers is required for good material properties; therefore, short fibers are used in contrast to, Figure 5. Calculated temperature profiles after an accident with a total loss of all coolant.…”

Fiber Volume Fraction Influence on Randomly Distributed Short Fiber Tungsten Fiber‐Reinforced Tungsten Composites

“…[5][6][7][8][9] Relying on an extrinsic toughening principle, even in the brittle regime, this material allows for a certain tolerance toward cracking and damage in general in comparison to conventional W. [5,[10][11][12][13][14] In general, similar to the ceramic fiber-reinforced composites, a relatively weak interface between the fiber and the matrix is considered to be beneficial to achieve the so-called pseudoductility. [10,13,[15][16][17] In previous studies, the W f /W material is mainly produced by chemical vapor deposition (CVD) process. [9,14,18,19] However, powder metallurgy (PM) processes are the main manufacturing routes to produce W material in industry.…”

“…Relying on an extrinsic toughening principle, even in the brittle regime, this material allows for a certain tolerance toward cracking and damage in general in comparison to conventional W . In general, similar to the ceramic fiber‐reinforced composites, a relatively weak interface between the fiber and the matrix is considered to be beneficial to achieve the so‐called pseudoductility …”

Insight into the Microstructure and Tensile Behavior of the W–Cu Composite Reinforced with Tungsten Fibers and Particulates

“…[5][6][7][8] More fortunately, the principle concept of "tungsten fiber (W f )-reinforced W composites overcome the brittleness of W" has been demonstrated [9] by the toughening effect on the composite consisting of a single W f embedded in the tungsten matrix [10] and the pseudo-ductile behavior in pushout experiments and ANSYS simulation. [11] On the other hand, it should be pointed out that W-Cu composites benefiting from the high strength of W and high conductivity of Cu are candidate heat sink materials for highly heat-loaded plasma-facing components. [12,13] Moreover, W-Cu functionally graded composites are considered over carbon/carbon fiber composites to transfer heat loads and plasma-induced erosion.…”

“…[ 5–8 ] More fortunately, the principle concept of “tungsten fiber (W f )‐reinforced W composites overcome the brittleness of W” has been demonstrated [ 9 ] by the toughening effect on the composite consisting of a single W f embedded in the tungsten matrix [ 10 ] and the pseudo‐ductile behavior in pushout experiments and ANSYS simulation. [ 11 ]…”