Actual concepts for -TiAl alloy and process …c.ymcdn.com/sites/ EUROPE 2015 • May 11-13 • Birmingham Actual concepts for -TiAl alloy and process development Florian Pyczak Institute

Titanium EUROPE 2015 • May 11-13 • Birmingham

Actual concepts for -TiAl alloy and process development

Florian Pyczak

Institute of Materials Research, Helmholtz-Zentrum Geesthacht, GermanyProfessorship Microstructural Materials Design, BTU Cottbus-Senftenberg, Germany

Outline

2Titanium EUROPE • May 2015 • Birmingham • Florian Pyczak • Helmholtz-Zentrum Geesthacht

• TiAl and TiAl alloys – an introduction

• Actual forged TiAl alloys

• Powder metallurgy of TiAl alloys

Introduction TiAl

•Low density 3.7 - 4.2 g/cm3

•Good creep resistance

•Excellent oxidation resistance


Introduction TiAl

100 mTitan Aluminium


Ti-48Al-2Cr-2Nb (cast)

-TAB (cast)


-TAB (cast)

TNB-V5 (Ti-45Al-5Nb-0.2C-0.2B) (cast)


-TAB (cast)

TNB-V5 (Ti-45Al-5Nb-0.2C-0.2B) (cast)

TNB-V5 (Ti-45Al-5Nb-0.2C-0.2B) (extr.)

Introduction TiAl


Introduction TiAl

Addition of-stabilisingelements asNb, Mo, ….

Bolz, Oehring, Lindemann, Pyczak, Paul, Stark, Lippmann, Roth-Fagaraseanu, Schreyer, Weiß, Intermetallics 2015


PAGE 7

Generation 3: e.g. TNM and TNB-V4

Ti-43-45Al-4-10Nb-0-2Mo-(0-0,3)B-(0-0,3)C

Low aluminium content

-stabilisation

Grain refinement

Precipitation hardening

Titanium EUROPE • May 2015 • Birmingham • Florian Pyczak • Helmholtz-Zentrum Geesthacht 7

Actual forged TiAl-alloys

Low aluminium content

-stabilisation

Grain refinement

Precipitation hardening

Aim fine grained, equiaxed duplex microstructure with low /B2-content

2 step heat treatment:

A) Dissolve /B2 but retain fine grain structureB) Adjust microstructure of 2, (and few B2) and stress reduction

AB

Heat treatment and mechanical properties


A) Dissolve /B2 but retain fine grain structure




1250 °C 1300 °C1270 °C

B2 increases Grains coarsen

B) Adjust microstructure of 2, (and few B2) and stress reduction




(air cooled) 6h @ 800 °C (air cooled) 2h @ 1000 °C

B2-fraction increases and fewer lamellar colonies

PAGE 11

Why no influence of higher B2-fraction on creep strength?Bolz, Oehring, Lindemann, Pyczak, Paul, Stark, Lippmann, Roth-Fagaraseanu, Schreyer, Weiß, Intermetallics 2015



200 nm

PAGE 12

B2-grain

0 entlang [0001] ZA

Phase constitution morecomplex than initially

thought




PAGE 13

• Induction coil: frequency of 150-250kHz, max. power 100kW• gas nozzle: ring slit type (Ø 20mm) with Argon

pre-alloyed rod

conical induction coil

ring slit nozzle (Ar)

High Reactivity of TiAl-melt => high demands on atomisation process / equipment

EIGA:Electrode Induction

Melting Gas Atomization


Powder Metallurgy

PAGE 14

150 m


Powder Metallurgy

PAGE 15

Chemicalde-binding

Injectionmoulding

Powder

Mixing withbinder

Thermalde-binding

and sintering

FinishedPart


Metal Injection Moulding

PAGE 16

Oxygen:1150 µg/g

Porosity:< 0.5 %

Colony size:60 µm

UTS [MPa] YS [MPa] pl [%]

RT 615 - 0.15

700 °C 583 490 0.5

TNB-V5, 2h, 1500°C, Vacuum, rapid cooling

UTS [MPa] pl [%]

745 0.1

720 1.4

MIM Guß



Limberg, Ebel, Pyczak, Oehring, Schimansky, MSE-A 2012

BMBF-report 03 N 3108 A Daimler Chrysler

900 °C

800 °C

700 °C

Ti-45Al-5Nb-0.2C-0.2B cast and HIP‘ed



Ti-45Al-5Nb-0.2C-0.2B MIMSt

ress

[MPa

]

Time [h]

Summary

• TiAl alloys are attractive light weight high temperature materials

• Actual forged TiAl alloys have a huge potential for property optimisation by heat treatment

• Powder Metallurgy can produce near net-shape TiAlparts equal in mechanical properties to cast material


19MSE 2014 • 23.09.2014 • Darmstadt

Thank youfor

attention!your

Wolfgang LimbergJuliano Soyama Thomas EbelMichael OehringSebastian Bolz

Actual concepts for -TiAl alloy and process …c.ymcdn.com/sites/ EUROPE 2015 • May 11-13 • Birmingham Actual concepts for -TiAl alloy and process development Florian Pyczak Institute

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