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June.2003
Hiroshi Harada
Project Director, HTM21
National Institute for Materials Science, Japan
As part of "Leading Programme towards Independent Administrative Organisation", NIMS (NRIM at that time) launched an R&D project "High Temperature Materials 21" Project, the Phase 1 (1999.6-2004.3), extended for 2 years until 2006.3.
In this Project we develop high temperature materials for advanced power engineering systems, including ultra-high efficiency gas turbines for power generation, advanced jet engines, high performance space rockets and so on. Flexibility and productivity of research, technology transfer, international development, etc are the key words.
We develop Ni-base superalloys, ceramics(Si3N4), and refractory superalloys, which are the three materials that are the basisof this project. To enhance the practical use of the new materials we develop a virtual gas turbine in computers to evaluate the materials performance before actual tests in gas turbines. We also conduct fundamental researches on materials design and analysis to enhance the materials development.
We have clear targets for developments of the three kinds of materials. The temperature capability under 137MPa for 1000h creep rupture is to be 1100C for Ni-base superalloys, 1500C for ceramics, and 1800C for refractory superalloys.
The budget is ¥200,000,000(1.5M.US$)/year. About 30 people are dedicated to this Project, including international collaborators.
Computer simulations of microstructures and properties by both theoretical and empirical approaches with mainly Ni-base superalloys and Ir-base refractory superalloys.
Approaches include:
(1) Statistical Thermodynamics
Cluster Variation and Monte Carlo simulations for multi-component superalloys containing Re, Ir, etc.
(2)Thermodynamics
An equilibrium calculation model for multi-component Ni-base
superalloys, containing platinum group metals, etc.
(3)Phase Field Method
Microstructural evolution in superalloys, e.g, solidification,
precipitation, coarsening, etc. are dealt with.
(4)FEM
Stress/strain calculation for microstructures in Ni-base superalloys.
(5)Empirical approach
Database and regression analysis: Alloy Design Program being licensed
to Rolls Royce.
Microstructure evolution during processing and service is being analysed in different scales.
Techniques employed include:
(1)APFIM
Phase equilibrium, site occupation, composition profile at
phase interface, etc. in multi-component Ni-base superalloys.
(2)TEM
A 400KV TEM equipped with high temperature tensile holder is being installed for in-situ observations of microstructure evolution and dislocation motion during creep.
(3)High Temperature X-ray Diffractometry
An X-ray Diffractometer with a hot stage (up to 1200C) is being used for misfit and lattice distortion measurements in coherent/ semi-coherent γ/γ' structures.
(4)Elastic moduli measurement
Elastic moduli measurement is being made with a new equipment up to 1100C.
(5)Creep analysis
Creep behaviour of SC/DS superalloys, e.g., 3 rd/4 th generation
alloys, is being analysed in connection with the microstructural
parameters above.
Single crystal (SC) and directionally solidified (DS) superalloys are being developed under collaborations with private companies.
(1)Large gas turbines for combined cycle power plants
Development of new SC superalloys and its application to
actual gas turbines. A NIMS 3rd generation SC superalloy,
TMS-75, and a newly developed SC superalloy, TMS-82+,have been
tested in a 15MW industrial gas turbine (1999.12 - 2002.3).
(2)Small gas turbines for co-generations, etc.
Development of new SC/DS superalloys with higher temperature capabilities as well as better hot corrosion resistance is being conducted.
(3)Jet engines
Development of 4 th generation superalloys is being carried out. TMS-138/139 with 2/3wt% Ru/Ir have been developed.
(4)Rejuvenation
Heat treatment conditions for rejuvenation of SC superalloys, and otheer superalloy developments are being carried out.
We have reached the target temperature 1100 C, as 1000 h/ 137MPa creep rupture temperature last year.
Si3N4 base ceramics with controlled grain boundary structures are being investigated.
Yb and Lu additions with some other ceramics to crystallise the glass phases at grain boundaries is successfully applied.
We have reached the temperature capability of 1450oC, getting closer to the final target of 1500oC.
Ultra-high temperature alloys with fcc/L12 coherent structures are being developed, including:
(1)PGMs(Ir,Rh,Pt,etc)-base refractory superalloys
Ir/Rh-X (X= Nb,Hf,Zr , etc) binary, ternary, quaternary, etc, alloys. Effects of L12 volume fraction, lattice misfit, morphology, etc on mechanical properties, deformation mechanisms, etc.
(2)Increasing the ductivity of the refractory superalloys
Additions of minor elements including B, C, etc. as well as
major additions of Ni etc. for ductilisation.
(3)Mixing PGMs-base and Ni-base superalloys
Balancing of the cost performance, specific weight, ductility, etc is being
investigated by mixing the two superalloys in a different fractions.
etc.
We have reached the temperature capability of 1750oC, getting closer to the target set at 1800oC.
Development and evaluation of new coating systems are being conducted.
(1) Bond coat
PGMs and their based alloys are being investigated as possible new coating materials for higher gas temperatures up to 1700 C.
(2) Top coat
New ceramics for next generation coating systems will be investigated.
A virtual gas turbine system is being constructed to be used on personal computer by combining CFD, heat transfer analysis, and stress analysis programs with materials simulation programs.
A prototype virtual gas turbine has been constructed and is ready to open to the WWW.