Texture of Metals

Typical Textures in Metals

Texture of Metals

1. Deformation Textures in fcc Metals2. Deformation Textures in bcc Metals3. Deformation Textures in hcp Metals4. Deformation Textures in Other Materials5. Composites6. Transformation Textures7. Texture Heterogeneities8. Solidification and Thin Film Textures

Contents

Texture of Metals

Deformation Textures in fcc Metals

Fiber textures (compression)

Rolling textures

Torsion texture (simple shear)

Texture of Metals

Fiber textures (Compression of Al, Cu, Ag, Brass)

Axisymmetric deformationTension compression

Only one direction to fully characterize the textures

Initial texture

simulated texture

experimental texture

Texture of Metals

Rolling textures (Variation with Strain)

Effect of strain on polycrystalline rolling textureSame texture Stronger and sharper texture

Fig. 111 pole figure (RD vertical)for rolled Cu

(a) 0 %, (b) 35%, (c) 58%, (d) 82%, (e) 90%, (f) 95%

Texture of Metals

Rolling textures (Variation with Material)

Fig. 111 pole figures for Cu-Zn alloys cold-rolledto 96% reduction with varying Zn content

Effect of alloying content on polycrystalline rolling texturecopper texture : pure metal type texture brass texture : alloy type texture

< 15% Zn

> 15% Zn

Texture of Metals

Rolling textures (Variation with Temperature)

Effect of temperature on polycrystalline rolling texturehigh temp. : pure metal type texture (copper)low temp. : alloy type texture (brass)

- 80oC - 150oC

- 196oCFig. 111 pole figures for Pu-9.6Ga rolled 95%

Texture of Metals

Rolling textures (Fiber and component analysis)

Two common approaches to analyzing rolling texture

1. Using texture component : to reduce the presentation of OD

into specific orientations

2. Using fibers: a single degree of freedom about a fixed axis: α- fiber : brass-Goss

β- fiber : copper-S-brass: not fixed in position

Texture of Metals

Rolling Textures (Fiber & Component Analysis)

Texture of Metals

Torsion textures (Simple Shear)

Usefulness of torsion test

: obtaining large plastic strains without friction

effect at interface btw specimen and platen

Specimen preparation

: surface layer separation + flattening

Texture of Metals

Texture of Metals

Shear Texture

• Shear strain means that displacements are tangential to the direction in which they increase.

• Shear direction=1, Shear Plane ⊥ 2-axis

ε12

1 = Shear Direction = <uvw>

2 =Torsion Axis= {hkl}

dε =0 +∆ 00 0 00 0 0

Texture of Metals

Torsion Textures :Twisting of a Hollow Cylinder Specimen

(a)

(b)(c)

Torsion Axis

Texture of Metals

{111}<uvw>

Torsion textures (ideal orientation)

{hkl}<110>

{001}<110>

Torsion axisShear plane

Shear direction

Texture of Metals

Shear Texture Components

• Why study shear textures? Shear strain near the surface of rolled parts

• Partial Fibers: A/D {111}<uvw>…<110>B {hkl} <110> … {112}

Components C {001}<110>D {112}<111>E {011}<111>F {110}<001>

Texture of Metals

{100} Pole figuresMontheillet et al.,

Acta metall., 33, 705, 1985

fcc bcc

Texture of Metals

fcc Torsion Textures

Plots of {111} and {200} pole figures (equal area projection; torsion axis vertical) for the following materials deformed in torsion; the shear direction points to the left in these figures.a) Nickel at γ=3.6b) Copper at γ=3.5c) Silver at γ=3.5d) Cu-30Zn at γ=3.5e) Ni-60Co at γ=3.2

Note that the partial "A" fiber is present in Ni and Cu, but is absent in the other materials. Silver, brass and Ni-60Co show instead a "D" fiber which is similar to the A fiber but rotated approximately 90° about the torsion axis. The B fiber is present to varying degrees in all the materials.

Texture of Metals

Torsion Textures (variation with material)

(a) Ni

(b) Cu

(c) Ag

(d) Cu-30Zn

(e) Ni-60Cu

γ = 3.2 ~ 3.6

Texture of Metals

Torsion Textures (Reversibility)

Assumption : single phase materialszero net strain (in reverse twist)

Irreversibility of work hardening :Accumulation of stored dislocation is sign-insensitive

Reversibility of texture evolution :

Texture development depends on accumulated changes in grain shapes

Expectation for reversion of texture evolution

Texture of Metals

Initial texture

γ = 3.5

Zero net strain

Irreversibility of Texture Evolution

111 and 200 pole figures for Al (99.99%)

Texture of Metals

Deformation Textures in bcc Metals

Comparing textures in fcc and bcc metals

Fiber textures (tension of Ta)

Rolling textures (Ta, steel)

Torsion texture (Fe)

Texture of Metals

Comparing textures in fcc and bcc metals

)()()()( ˆˆ sj

si

ssij nbL γ&=

( ))()()()()( ˆˆˆˆ si

sj

sj

si

sij nbnbm +=

21

( ))()()()()( ˆˆˆˆ si

sj

sj

si

sij nbnbq −=

21

( ) )()()()()()( ˆˆˆˆ sij

fccsi

sj

sj

si

sij

bcc mbnbnm =+=21

( ) )()()()()()( ˆˆˆˆ sij

fccsi

sj

sj

si

sij

bcc qbnbnq −=−=21

b̂n̂

L : velocity gradient

: slip direction

: slip plane normal

: symmetric part of distortion tensor

: skew part of distortion tensor

Texture of Metals

In Uniaxial deformationTexture developed in tension of fcc

= Texture developed in compression on bcc

In RollingInterchange of RD and ND for fcc and bcc

Comparing textures in fcc and bcc metals

Texture of Metals

: Rolled Copper (80%)

: Rolled Fe-3Si (80%)

Comparing Textures in fcc and bcc Metals

Texture of Metals

Fiber Textures (Tension of Ta)

: Rolled Ta (92%)

: in tension of 0.6 of (a)

Bcc metals under tensile deformation : <110> fiber(equivalent under wire drawing)

Texture of Metals

Rolling Textures (Ta, steel)

Position of ideal fibers for bcc materials

Texture of Metals

Peak intensity shift of fiber textures with strain

α-fiber : {001}<110> {112}<110>γ-fiber : {111}<112> {111}<110>

φ

ϕ1

ϕ2 =45ο

Rolling Textures

Texture of Metals

Rolling textures (Variation with Alloying Content)

: Hot rolled Fe-XSi

: Cold rolled Fe-XSi

Texture of Metals

Torsion texture (Fe, Ta)

Fewer publication than for fcc

Shear texture in bcc{112}<111>, {110}<001>

shear textures in fcc: {111}<uvw>, {hkl}<110>, {001}<110>

Texture of Metals

Deformation Textures in hcp Metals

Fiber textures( extrusion & compression)

Rolling textures

Tube textures

Texture of Metals

Twinning almost always provides significant deformation modes (texture)

slip: gradual lattice rotation with straintwinning: large scale lattice rotation

even for low strain

Zr alloy (Zircaloy)Ti alloys

Deformation Textures in hcp Metals

Texture of Metals

Fiber Textures ( Extruded Ti & Compressed Ti)

: extruded Ti

: compressed & cross rolled Ti

Extrusion axis

[1124]

ND

Texture of Metals

Rolling textures

Three groups according to c/a ratio

c/a > 1.633 : Zn, Cd

c/a = 1.633 : Mg, Co

c/a < 1.633 : Zr, Ti

Texture of Metals

Rolling textures

Mg

Zn

Ti

Fig. 0002 pole figures for rolled Mg, Zn, Ti.

Texture of Metals

Rolling textures

Roles of slip and twinning on rolling

Fig. 0002 pole figures for cold-rolled Ti(a) 20%, (b) 30%, (c) 55%, (d) 97%

low strain (<40%) major deformation mode : twining

high strain (>40%)major deformation mode : slip

Texture of Metals

Tube textures (Zircaloy)

Rw: reduction in wall thicknessRD: reduction in diameterεR: radial strainεT: tangential (or hoop) strain

Rw /RD >1: similar to rolling

Rw /RD =1: similar to wire drawing

Texture of Metals

Deformation Textures in intermetallics (NiAl)

Fig. Inverse pole figures for NiAl

Starting extruded at R.T extruded at 300oC

NiAl: low ductility at R.T, extensive g.b cracking Hydrostatic extrusion

Texture of Metals

1. Deformation Textures in fcc Metals2. Deformation Textures in bcc Metals3. Deformation Textures in hcp Metals4. Deformation Textures in Other Materials5. Composites6. Transformation Textures7. Texture Heterogeneities8. Solidification and Thin Film Textures

Part-2

Texture of Metals

Composites

Wire-drawn Cu-Nb composite

Extruded Al-SiC composites

Rolled Be-Al composites

Texture of Metals

Wire-drawn Cu-Nb composite

Expectationtexture in composite : “rule of mixtures” approach

Fig. Inverse pole figures for wire drawn Cu-Nb composite

Cu matrix(fcc)

Nb reinforcement(bcc)

Texture of Metals

Extruded Al-SiC(whisker) composites

Fig. Pole figures for extruded 8090 Al alloys with SiC whisker

0 %

15 %

30 %

Texture of Metals

Extruded Al-SiC(particle) composites

Fig. Pole figures for extruded 8090 Al alloys with 15% SiC particles

whisker : more effective at repressing texture development

Texture of Metals

Transformation Textures

Phase transformation

Recrystallization in rolled fcc metals

Texture of Metals

Phase transformation

Orientation relationship between parent phase and product phase :

Alignment of close-packed plane and direction

Kurdjumov-Sacks (KS) relationship

{111}fcc // {110}bcc <110>fcc // <111>bcc

Texture of Metals

at T>TR

Hot rolled steel :

{001}<100>

{001}<110>

{110}<001>

{110}<110>

Phase transformation (in steel)

In austenite (fcc) In ferrite (bcc)

Texture of Metals

Phase transformation (alloying effect)

Plain carbon steel Nb alloyed steel

Alloy addition : raising recrystallization temperature

ϕ2 =45o

Texture of Metals

Recrystallization in rolled fcc metals

Recrystallization texture : more complicate thanphase transformation texture

No texture change in recrystallization1. Large volume fraction of 2nd phase particles2. Axisymmetric deformation

Texture of Metals

Precipitation state

Recrystallization texture

Stacking fault energy Deformation state

Annealing temp.

Recrystallization texture

Texture of Metals

Fig. Recrystallization textures of cold rolled metals

Al Cu

Brass Al-Mn(A3103)

Recrystallization texture (material dependence)

BR: {236}<385>

Texture of Metals

Recrystallization texture (bcc)

coarse 2nd phase particle : weak recrystallization textureeffect of Mn in low carbon steel : decrease <111><111>//ND fiber , <110>//RD fiber [Raabe &Lucke, 1992]

Low carbon steel

Texture of Metals

Recrystallization texture (Cu)

Fig. 111 pole figures for recrystallized Cu

71 %

100 %91 %

45 %

11 %0 %

Texture of Metals

Recrystallization texture (Cu)

Fig. Volume fraction of major components in recrystallization of 90% rolled Cu

Effect of recrystallized fraction

Texture of Metals

Recrystallization texture (Cu)

Effect of prior strain

Fig. Volume fraction of cube component in recrystallized Cu

Texture of Metals

Texture Heterogeneities

Local heterogeneities in deformation

Texture gradient after deformation

Heterogeneities in recrystallization

Texture of Metals

Local heterogeneities in deformation

Grain-scale heterogeneities

Individual grains : subdivided into regions with a range of orientation

Deformation of polycrystalline

In cold-rolled polycrystalline Al [by Hansen, 1992]3o at 5 %, 15o at 20%, 20o at 30%

Texture of Metals

Multi-grain heterogeneities: local texture of shear band

Initiation at stress riser(corner or edge of rolled sheet)

Not significant contribution to global textureAffect subsequent recrystallization texture

Local heterogeneities in deformation

Texture of Metals

Most forming process : not uniform spatial distribution of texture

Surface-to-midplane gradient in rolled materials

Surface-to-core gradient in wire

Outer-to inner wall gradient in tube

Texture gradient after deformation

Texture of Metals

1. In rolling

Surface frictionRoll geometryRolling temperature

Texture gradient after deformation

Fig. 111 pole figures from rolled Fe-3%Si

Texture of Metals

Texture gradient after deformation

2. In wire drawing

Fig. 111 pole figures from drawn Al wire

R < 1mm R = 1.4mm

R = 1.8mm R = 1.95mm

Texture of Metals

3. In tube extrusion

Fig. Different types of texture gradient for zircaloy tubing

εR : radial strain

εT : tangential strain

OD: out diameter

ID : inner diameter

Texture gradient after deformation

Texture of Metals

Fe-3%Si sheet : used in transformer{110}<001> Goss texture

Hot rolling Cold rolling Recrystallization

Shear texture in bcc : {112}<111>, {110}<001>

Rolling texture in bcc : α+ γ fiber

Goss

α+ γ fiber

Goss

{111}<112>

α+ γ fiber

{111}<112>

Goss

α+ γ fiber

Goss

Heterogeneities in recrystallization

Texture of Metals

Grain growth of Fe-3%Si sheet (<1mm)

Heterogeneities in recrystallization

• Key factor : oxygen content

Low content (vacuum) : {110}<001> Gossγ110 < γ100

Presence of oxygen : {001}<100> Cubeγ110 > γ100

Texture of Metals

Solidification and Thin Film Textures

Solidification

Vapor deposition

Electrodeposition

Texture of Metals

Solidification (Cast Inconel)

Preferred Growth Direction of Dendrite in Cubic : <100>

Grain boundary map and 100 pole figures for cast Inconel X750

0~0.1mm 0.1~0.2mm 0.2~0.3mm

0.6~0.9mm 1.2~1.5mm 1.8~2.1mm

Texture of Metals

Solidification (Melt-Spun Pd-In Ribbon)

Bottom

Top

100 and 111 pole figures for melt-spun Pd-In

20o

20o

Texture of Metals

Vapor Deposition (CVD Ta)

Vapor Deposition : Strong fiber textureSelecting Plane to measure texture

100 pole figure CVDed Ta

Texture of Metals

Vapor deposition (sputtered Al)

sputtering : stronger texture than evaporation

electromigration in Al interconnectstrong <111> fiber : longer lifetimet <111> = 10 . t<110> [Joo & Thompson, 1994]

Texture of Metals

Electrodeposition

Texture of electrodeposits depend on1. Crystal structure of substrate and deposit 2. Bath conditions :

bath composition, current densityvoltage, temperature, pH

If difference btw asub and adepo > 15% : deposit texture depend on bath condition

If asub≒ adepo :initial layer : epitaxial growthintermediate layer : depend on bath condition

Texture of Metals

Summary

What materials ? What processing ?+

Metallurgical variables

Illustration of complexity and richness in texture development

Expectation of texture development