A simulation study on deformation behavior of

tungsten fiber reinforced copper matrix nanowire

Subodh Rana1 & Natraj Yedla2

1. Dept. of Metallurgical and Materials Engineering, NIT Jamshedpur

2. Dept. of Metallurgical and Materials Engineering, NIT Rourkela

TECHNICA ‘ 2014,

Introduction

Tungsten wirewww.gd-wholesale.com

Copper sheetwww.gd-wholesale.com

A

B

Tungsten fiber reinforced copper matrix compositewww.emeraldinsight.com

Interface

Matrix Fiber

C

Representative volume cell

• Fabricated by liquid phase infiltration.

•Continuous unidirectional tungsten fibers were packed in ceramic tubes to the desired fiber content.

•A slug of copper was placed above the fiber bundle, and the assembly was placed in a furnace and heated to 1478 K (2200 °F) for 1 hr in either a vacuum or hydrogen atmosphere.

Applications of W/Cu composite

• High Temperature aircraft- high creep resistant

• Rocket engine turbine

• High strength electrical conductor- strength by resistivity ratio 10 times higher than other

Takes initial

configuration

Calculates

potential

Obtain Force

Finds velocity

and position

Ends if last timestep is

reached

M D Simulation

Velocity-verlet integration with 2 fs timestepv(t+∆t)=v(t)+a(t)∆tr(t+∆t)=r(t)+v(t)∆t+1/2a(t)∆t

Gradient of potentialF=-dU/dr=ma

Taking configuration

and potential

method, EAM,

MEAM, tersoff, etc

Checks timestep

Simulation models and Parameters

Copper atom

Tungsten atom

Tungsten fiber reinforced copper nanowire

r=5Å

Copper nanowire before reinforcement

r=20Å

• Critical fiber length Lc = (σf*d)/2Tc = 2.2 nm{(16*5)/(2*18)= 2.2 }

•Rule of mixture: σc=σf*Vf +σm*Vm

Kc=Kf*Vf+Km*Vm

• There is insolubility between tungsten and copper

Results and discussions

at 0.5%/ps strain rateT= 300 K(G

pa)

(Å/ Å)

Engineering stress strain plot

• Increased in yield strength observed

• Presence of Tungsten Fiber delays the onset of necking

VMD snapshots at strain of 150 %

A B

Experimental Engineering strain stress curve(Review David L. McDanels, Lewis research centre, NASA, Tungsten Fiber Reinforced Copper Matrix Composites)

Comparison with experiment

Conclusions

• Reinforcement of Tungsten fiber increased the strength of the Cu matrix

•The yield strength of composite is ~4.5 Gpa

• The high strength to resistivity ratio makes it usable as high strength electrical conductor

• Use of this composite as structural component in space craft reduces its weight high strength by weight ratio

Refernces

[1] He, L.H., Lim, C.W., Wu, B.S., 2003. A continuum model for size-dependent deformation of elastic films of nano-scale thickness.Int.J.Solids Struct.41 (3–4), 847–857[2] University of Virginia, MSE 4270/6270: Introduction to Atomistic Simulations, Leonid Zhigilei[3] http://lammps.sandia.gov/doc/Manual.html[4] R.A. Johnson, Physics Rev, B37, 1988, 6121[5] http://www.crystallography.fr/mathcryst/twins.htm[6] Jeong-Won Kang and Ho-Jung Hwang, Mechanical deformation study of copper nanowire using atomistic simulation, Nanotechnology 12 (2001) 295–300[7] P.R. Subramanian and D.E. Laughlin, Cu-W (Copper Tungsten), Indian Institute of Metals, Calcutta, 1991, pp. 76-79[8] Dalvid-L. McDanels, Tungsten Fiber Reinforced Copper Matrix Composites, NASA Technical Paper 2924, 1989[9] David L. McDanels, Robert W. Jech, andJohn W. Weeton;Lewis Research Center Cleveland, Ohio, Stress-Strain Behaviour Of Tungsten-Fiber-Reinforced Copper Composites, NASA TN D-1881

Thank You