High Temperature Resistant Intermetallic Nial-Based Alloys with Refractory Metals Cr, Mo, Re - Structures - Properties - Applications -

2002 ◽  
Vol 753 ◽  
Author(s):  
G. Frommeyer ◽  
R. Rablbauer

ABSTRACTThe stoichiometric intermetallic compound NiAl with B2 superlattice structure exhibits superior physical and high-temperature mechanical properties, and excellent oxidation resistance. The main disadvantages of polycrystalline NiAl are the lack in plasticity and fracture toughness below the brittle-to-ductile-transition temperature of about 550°C. Insufficient high-temperature strength and creep resistance occur at temperatures above 800°C. Despite these facts NiAl-based alloys are still considered as promising structural materials for high-temperature applications. The refractory metals Cr, Mo, and Re with b.c.c. and h.c.p. lattice structures form with NiAl quasi-binary eutectic systems, showing high melting temperatures and thermally stable microstructures. Elasticity, solid solution hardening, fibre reinforcement, and creep properties were investigated in view of the constitutional defect structure and microstructural features. Especially the fibre reinforced NiAl matrix composites possess optimum high-temperature strength up to 1200 °C, and improved creep resistance as well.

2006 ◽  
Vol 510-511 ◽  
pp. 358-361
Author(s):  
Won Yong Kim ◽  
Han Sol Kim ◽  
In Dong Yeo ◽  
Mok Soon Kim

We report on advanced Ni3Al based high temperature structural alloys with refractory alloying elements such as Zr and Mo to be apllied in the fields of die-casting and high temperature press forming as die materials. The duplex microstructure consisting of L12 structured Ni3Al phase and Ni5Zr intermetallic dispersoids was observed to display the microstructural feature for the present alloys investigated. Depending on alloying elements, the volume fraction of 2nd phase was measured to be different, indicating a difference in solid solubility of alloying elements in the matrix γ’ phase. Lattice parameter of matrix phase increased with increasing content of alloying elements. In the higher temperature region more than 973K, the present alloys appeared to show their higher strength compared to those obtained in conventional superalloys. On the basis of experimental results obtained, it is suggested that refractory alloying elements have an effective role to improve the high temperature strength in terms of enhanced thermal stability and solid solution hardening.


Author(s):  
M. G. Burke ◽  
M. N. Gungor ◽  
M. A. Burke

Intermetallic matrix composites are candidates for ultrahigh temperature service when light weight and high temperature strength and stiffness are required. Recent efforts to produce intermetallic matrix composites have focused on the titanium aluminide (TiAl) system with various ceramic reinforcements. In order to optimize the composition and processing of these composites it is necessary to evaluate the range of structures that can be produced in these materials and to identify the characteristics of the optimum structures. Normally, TiAl materials are difficult to process and, thus, examination of a suitable range of structures would not be feasible. However, plasma processing offers a novel method for producing composites from difficult to process component materials. By melting one or more of the component materials in a plasma and controlling deposition onto a cooled substrate, a range of structures can be produced and the method is highly suited to examining experimental composite systems. Moreover, because plasma processing involves rapid melting and very rapid cooling can be induced in the deposited composite, it is expected that processing method can avoid some of the problems, such as interfacial degradation, that are associated with the relatively long time, high temperature exposures that are induced by conventional processing methods.


Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 384
Author(s):  
Andong Du ◽  
Anders E. W. Jarfors ◽  
Jinchuan Zheng ◽  
Kaikun Wang ◽  
Gegang Yu

The effect of lanthanum (La)+cerium (Ce) addition on the high-temperature strength of an aluminum (Al)–silicon (Si)–copper (Cu)–magnesium (Mg)–iron (Fe)–manganese (Mn) alloy was investigated. A great number of plate-like intermetallics, Al11(Ce, La)3- and blocky α-Al15(Fe, Mn)3Si2-precipitates, were observed. The results showed that the high-temperature mechanical properties depended strongly on the amount and morphology of the intermetallic phases formed. The precipitated tiny Al11(Ce, La)3 and α-Al15(Fe, Mn)3Si2 both contributed to the high-temperature mechanical properties, especially at 300 °C and 400 °C. The formation of coarse plate-like Al11(Ce, La)3, at the highest (Ce-La) additions, reduced the mechanical properties at (≤300) ℃ and improved the properties at 400 ℃. Analysis of the strengthening mechanisms revealed that the load-bearing mechanism was the main contributing mechanism with no contribution from thermal-expansion mismatch effects. Strain hardening had a minor contribution to the tensile strength at high-temperature.


2020 ◽  
Vol 51 (12) ◽  
pp. 6195-6206 ◽  
Author(s):  
S. Giese ◽  
A. Bezold ◽  
M. Pröbstle ◽  
A. Heckl ◽  
S. Neumeier ◽  
...  

AbstractThe creep resistance of single-crystalline Ni-base superalloys at elevated temperatures depends among others on solid solution strengthening of the γ-matrix. To study the influence of various solid solution strengtheners on the mechanical properties, a series of Ni-base superalloys with the same content of different alloying elements (Ir, Mo, Re, Rh, Ru, W) or element combinations (MoW, ReMo, ReW) was investigated. Nanoindentation measurements were performed to correlate the partitioning behavior of the solid solution strengtheners with the hardness of the individual phases. The lowest γ′/γ-hardness ratio was observed for the Re-containing alloy with the strongest partitioning of Re to the γ-matrix. As a result of the creep experiments in the high-temperature/low-stress regime (1373 K (1100 °C)/140 MPa), it can be concluded that solid solution hardening in the γ-phase plays an essential role. The stronger the partitioning to the γ-phase and the lower the interdiffusion coefficient of the alloying element, the better the creep resistance. Therefore, the best creep behavior is found for alloys containing high contents of slow-diffusing elements that partition preferably to the γ-phase, particularly Re followed by W and Mo.


2000 ◽  
Vol 646 ◽  
Author(s):  
S.C. Deevi ◽  
W.J. Zhang ◽  
C.T. Liu ◽  
B.V. Reddy

ABSTRACTIn this paper, the mechanical and physical properties of a Ti-47Al-4(Nb, W, B) alloy (CTI-8) developed by Chrysalis Technologies are presented. The properties of CTI-8 alloy are compared with other TiAl-base alloys and currently used materials for high temperature applications. The CTI-8 alloy exhibits excellent creep resistance, good high temperature strength and better physical properties than the currently used materials. The comparisons suggest that CTI-8 has a great potential in aerospace and automotive industries.


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