Efficient oxidation protection of TiAl alloys by plasma immersion ion implantation of halogens

TiAl alloys

Attractive lightweight materials for advanced applications

 

  • Density 3.7 – 4.0 g/cm3

  • High melting point (~ 1600 °C)

  • Good mechanical properties at elevated temperatures

  • Good strength-to-mass ratio

  • Aerospace

  • Automobile

  • Power generation

 

Problem

Solution

Effect

Poor oxidation resistance at temperatures above 700 °C

Temperature range required for advanced structural applications: 700 ° – 1100 °C

Ion implantation of halogens, notably fluorine

Beamline ion implantation (BLII) 

Plasma based ion implantation (PBII) on PBII-7

TiAl alloys modified by ion implantation of fluorine acquire a stable, adherent and highly protective scale against environmental oxidation while retaining the bulk mechanical properties of the starting material. The protective scale is of good structural and mechanical integrity. As a result, a component made of such an alloy can be rendered highly resistant to oxidation in air or similar oxidizing environments at temperatures as high as 1100 °C.

Oxidationsverhaltens von γ-TiAl

 

ERDA Profile der Elemente in einer γ-TiAl

Comparison of the oxidation behavior of γ-TiAl before and after processing by BLII and PIII of F. Insets: As-received (untreated) turbocharger rotor (top left). Exposure in air at 1050 °C for 1200 h. The same rotor after fluorine treatment (bottom right). Exposure in air at 1050 °C for 1200 h.

 

ERDA profiles of the elements present in a γ-TiAl sample after optimized PIII of F (30 kV, 400 W, 750 Hz, 106 pulses). The efficiency of the PIII process is high resulting in implant times as short as about 20 min to inject F doses of 3 - 6x1017 cm-2.

γ-MET Probe

 

Turbinenblatt aus einer TNB Legierung

As-received γ-MET sample after isothermal oxidation in air at 900°C for 120 h (a). Metallographic cross-section of the same sample (b). γ-MET sample processed by PIII of F after isothermal oxidation in air at 900°C for 120 h (c). Metallographic cross-section of the same sample (d).

 

Jet turbine blade made of a TNB alloy after processing by PIII of F (a) followed by thermal cyclic oxidation in air at 720°C for 25 days (b). SEM/EDX analyses show the formation of a continuous protective alumina scale after F implantation and oxidation.

Projects:

"Einfluss einer oberflächennahen Dotierung auf die Oxidationskinetik von TiAl-Werkstoffen" (Volkswagenstiftung/I/72 726)

"Oxidationsschutz für neuartige Hochtemperatur-Leichtbauwerkstoffe durch Ionenimplantation (1)" (AiF Nr. 31ZBG)

"Oxidationschutz für neuartige Hochtemperatur-Leichtbauwerkstoffe durch Ionenimplantation (2)" (AiF Nr.104ZBG)

"Oxidationschutz für neuartige Hochtemperatur-Leichtbauwerkstoffe durch Ionenimplantation (3)" (AiF-Nr. 176 ZBG)

"Grenzen des Halogeneffektes für TiAl-HAT-Leichtbaulegierungen" (AiF-Nr. 177 ZN)

"Grenzen des Halogeneffekts für TiAl-Hochtemperaturleichtbaulegierungen unter industriellen Bedingungen (2)" (AiF 262 ZBG)

"Eine Haifischhaut für Hochtemperturanwendungen (1)" (DFG SPP 1299/sub)

"Eine Haifischhaut für Hochtemperturanwendungen (2)" (DFG SPP 1299/sub)

“Oxidationschutz für neuartige Hochtemperatur-Leichtbauwerkstoffe durch Ionenimplantation” (AiF-No. 176 ZBG)

DFG-Projekt im  DFG-Forschungsbereich SPP 1299 “Adaptive Oberflächen für Hochtemperaturanwendungen”; “Eine Haifischhaut für Hochtemperaturanwendungen: Strömungsoptimierte Schutzschichten“

Partners:

DECHEMA e.V. Frankfurt,

Rolls-Royce Deutschland,

MTU Aero Engines München,

GKSS,

TU Freiberg,

GfE Metalle und Materialien GmbH Nürnberg,

Universität Frankfurt/M,

Plansee,

DaimlerChrysler,

TechnoCoat,

Tital,

GfKORR