Download pptx - NCPCM 2015 FINAL ppt

Fabrication and Characterization of novel W80Ni10Nb10 alloy produced by

mechanical alloyingPresented by

Rishabh SaxenaNATIONAL CONFERENCE ON PROCESSING & CHARACTERIZATION OF MATERIALS (NCPCM 2015)

(12th December, 2015)

Contributing authors : R. Saxena, A. Patra, S. K. Karak, A. Pattanaik, S. C. MishraDepartment of Metallurgical and Materials Engineering

NATIONAL INSTITUTE OF TECHNOLOGY, ROURKELAROURKELA-769008

2

Brief outlineAims and Objective Introduction and Background Materials & Methods Result & Discussion Conclusions Future scope of work References

3

Aims and objective To fabricate W based alloys made by mechanical alloying, for kinetic energy

penetrator in defense application, structural applications in fusion reactors

designed for operation at higher (>550oC) operating temperature.

To characterize W80Ni10Nb10 alloy produced through mechanical alloying.

4

Radiation Shielding Aviation Counterweights

INTRODUCTION(Applications)

5

INTRODUCTION(Applications)

kinetic energy penetrators

6

Introduction & Background Why tungsten?• High melting point (34200C)• High hardness (9.8 GPa), Modulus of Elasticity=407 GPa. Good thermal conductivity (1.74 W/cm K) , low co-efficient of thermal expansion.• Low-activating metal in radiation environment with low

sputtering yield.(W.F. Smith, McGraw-Hill, 1993)

7

Introduction & BackgroundProblems?• High ductile brittle transition temperature.• Poor Oxidation resistance at elevated temperature.[Anshuman Patra, Microscopy and Anlysis , 26 (5), (2012)]

Why Nickel Addition ?• Improves ductility.• Promotes liquid phase sintering which can improve mechanical

(hardness) and Physical property (density).[Kemp et al., Jou. Of Less Common Metal, 175 (1991)]

8

Introduction & BackgroundNiobium Addition?• High melting point (2468°C).• To provide enhanced oxidation resistance at elevated temperature [ A.

Patra, Microscopy and Analysis, (2012)]

Why nanostructuring ?• To lower sintering temperature. [R. malewar et al., J. Mater. Res., 22 (2007)]

• To improve the mechanical properties. [H. Glieter, Acta. Mater., 48 (2000)]

9

Introduction & Background (Basis of Nickel Selection)

G. D. Samolyuk et al. Fusion Reactor Materials Program (2011)

Reduced peierls barrier (barrier to overcome for dislocation movement) & low cost as compared to other rare earth metals.

10

Materials and Method

Elemental W-Ni-Nb

Mechanical Alloying (20 h)

Compaction (500 MPa)

Sintering (1500°C, 2 h holding)

XRD at various milling times, SEM, TEM.

Density/Porosity

XRD,SEM

Hardness WearDensity

11

Materials and Method FRISTSCH planetary ball mill Room temperature milling Chrome steel vials and 10 mm balls 300 rpm, 10:1 (ball to powder weight) Wet milling with toluene Elemental powders of W, Ni, Nb (purity 99.5%, Sigma

Aldrich) with initial particle of 100-150 µm (for W, Ni, Nb)

MaterialDesignation

W(wt %)

Ni(wt %)

Nb(wt%)

M1 80 10 10

Composition (initial) of the powder blends for mechanical alloying /milling

12

Materials and MethodCompaction

Automatic hydraulic press (Uniaxial)

• 500 MPa pressure,

• 5 minutes holding time

13

Materials and Method Sintering Temperature: 1500°C. Sintering Furnace : tunnel type. Sintering Holding Time : 2 hrs Sintering atmosphere : Argon Flow rate of Argon: 100 ml/min.

Sintering Cycle.

14

Materials and MethodEquipment and Method Parameters measured

XRD (X-Pert High Score, Origin, Powdll software)

1. Crystallite size, Lattice strain, Lattice parameter, Dislocation density, phase evolution of milled powder

2. phase evolution in sintered product.

SEM Morphology and compositional study of milled powder.

TEM & SAD pattern Crystallite size determination and Crystal structure Indentification.

Archimedes’s principle Density/porosity measurement.Microhardness Tester Hardness evaluation (50,100,500,1000 gram-force load, 10 sec dwell

time)Ball on plate wear tester Wear study (load = 20 N,30N, time = 10 mins, speed= 25 r.p.m

15

Materials and Method

Crystallite size & Lattice strain calculation: sin (1)

β is the full width half maxima (FWHM), D is the crystallite size and is the lattice strain.[R. Jenkins et al. Introduction to X-ray Powder Diffractometry (1996)]

Dislocation density calculation: (2)

b : burgers vector of dislocations, b = (a√3)/2 for the bcc structure, a= cell parameter= lattice parameter, D = crystallite size, ε = lattice strain. (Zhao et al. Acta Mater, 2001)

16

Materials and MethodSintered Density Calculation:

(3): weight of the sintered sample in air. : weight of the sample with all the open porosity saturated with water, : weight suspended in water. : density of water. [Ozkan et al. J. Eur. Ceram. Soc , 1994]

Hardness Measurement: (4) GPa conversion= 0.009807 X HVP : applied load, d : diagonal length of the indentation. [ L. Ayers, The Hardening of Type 316 L Stainless Steel Welds with Thermal Aging, 2012]Sliding distance : R : number of rotation per minute traversed by the indenter on sample surface, t: time in sec (600 s), r : track radius (4 mm) measured from the center of the sample to the track. [ A. Patra, Microscopy and Analysis (2015)]

17

Results and Discussions XRD Study of Milled Powder

Fig. 1. XRD pattern of W80Ni10Nb10 alloy milled for 20 h.

18


Fig. 2. Variation of crystallite size and lattice strain of W with milling time in W80Ni10Nb10.

19


Fig. 3. Variation of a) Dislocation density and b) Lattice parameter of W in W80Ni10Nb10 with milling time.

20

Results and Discussions SEM Study of Milled Powder

Fig. 4. SEM images of powder morphology of W80Ni10Nb10 alloy after different milling times: (a) 0 h, (b) 5 h, (c) 10 h, and (d) 20 h.

21

Results and Discussions TEM Study of Milled Powder

Fig. 5. TEM image of W80Ni10Nb10 powder milled at 20 h: (a) Bright field TEM image and (b) corresponding SAD pattern.

22

Results and Discussions XRD Study of Sintered alloy

Fig. 6. XRD pattern of W80Ni10Nb10 alloy milled for 20 h and sintered at 1500°C for 2 h.

23

Results and DiscussionsSEM Study of Sintered alloy

Fig. 7. SEM micrograph of 20 h milled W80Ni10Nb10 alloy sintered at 1500°C for 2 h.

Calculated sinterability

24

Results and Discussions

Fig. 8. Variation of Hardness of W80Ni10Nb10 alloy milled for 20 h and sintered at 1500°C for 2 h.

Hardness Study

25


Fig. 9. Variation of wear depth of W80Ni10Nb10 alloy milled for 20 h and sintered at 1500°C for 2h.

Applied Load (N) Wear rate (× 10-15) m3/Nm 20 N 4.0130 N 4.43

J. Archard, J. Appl. Phys, 1953

Wear Study

26


Fig. 10. Micrograph of wear track at a) 20 N b) 30 N load

Wear Study

27

Conclusions W80Ni10Nb10 alloy powder can be effectively produced by mechanical alloying. Crystallite size of tungsten in W80Ni10Nb10 reduces with increasing milling time and

minimum crystallite size of 34 nm is achieved at 20 h of milling. Expansion of the lattice parameter of tungsten in W80Ni10Nb10 records 0.04% at 10 h and

contraction upto 0.02% at 20 h of milling. Bright field TEM image and corresponding SAD pattern reveals the presence of

nanocrystalline BCC-W phase with 20-30 nm in size at 20 h of milling. Presence of NbNi intermetallic is evident in the sintered alloy due to Ni rich liquid phase

formation at the selected sintering temperature. Microhardness value increases with decrease in load due to smaller indentation and

detection error of the diagonals of the indentation at lower loads. Wear rate at maximum wear depth increases with increase in load due to enhanced

abrasion effect at higher load.

28

Future scope of study Fabrication of alloy through advanced consolidation techniques (such as

spark plasma sintering) Improvement of high temperature strength through Oxide dispersion. Investigate the effect of increasing oxide content on mechanical properties of

W based alloy. Study the effect of increasing Nb content with respect to high temperature

response (oxidation behavior)

29

References[1] Patra A 2012 Microscopy and Analysis 26 (5) 14-15.[2] Glieter H 2001 Acta. Mater 48 1.[3] Koch C 1997 Nanostruct. Mater 9 13.[4] Suryanarayana C 1998 Mechanical Alloying ASM Handbook 7 80.[5] Suryanarayana C 2001 Prog. Mater. Sci 46 1-184.[6] Cullity B 1978 Elements of X-ray diffraction 2 (Addison Wesley: Philippines) 86-88.[7] Williamson G and Hall W H 1953 Acta. Mater 1 22.[8] Zhao Y H, Sheng H W and Lu K 2001 Acta. Mater 49 365–375.[9] Nuthalapati M, Karak S K, Majumdar J D and Basu A 2014 Metall. Mater. Trans. A 45A 3748-

3754.[10] Jenkins R and Snyder R L 1996 Introduction to X-ray Powder Diffractometry (J Wiley & Sons

Inc: New York).[11] Chattopadhayay P, Nambissan P M G, Pabi S K and I Manna 2001 Appl. Surf. Sci 182 308-

312. [12] Singh V 2002 Physical Metallurgy 1 (Standard Publisher Distributor: New Delhi) 63-64.[13] Patra A, Karak S K and Pal S 2015 Proc. Nat. Conf. on Processing and Characterization of

Materials (Rourkela) 75 (Bristol: UK/IOP Science) 012032.

30

References[14] Li X, Cheng Z, Hu K, Chen H and Yang C 2015 Vacuum 114 93-100.[15] Ozkan N and Briscoe B J 1994 J. Eur. Ceram. Soc 14 143-151.[16] Ayers L J 2012 The Hardening of Type 316 L Stainless Steel Welds with Thermal Aging

Massachusetts Institute of Technology.[17] Dieter G 1928 Mechanical Metallurgy SI Metric Edition (McGraw-Hill Co: Singapore)

189-93.[18] Patra A, Karak S K and Pal S 2015 Microscopy and Analysis 29(4) 18-22.[19] Nuthalapati M, Karak S K and Basu A 2015 Materials Today: Proceedings 2 1109- 1117.[20] Archard J F 1953 J. Appl. Phys 24 (8) 981-988.[21] Smith W. F, 1993 Structure and Properties of Engineering Alloys, Second Edition,

McGraw- Hill, USA, [22] Samolyuk G. D, Osetskiy Y. N, and Stoller R. E., 2011 Fusion Reactor Materials Program,

DOE/ER-0313/50, 50 124-128.[23] Kemp P. B. and German R. M., 1991 J. less common met. 175 353-368.

31

THANK YOU

32

QUESTIONS??