Heat-resistant RuAl-based alloys. Part I. Casting alloys

The article studies new heat-resistant and wear resistant materials for operation under extreme conditions, especially in the power industry. The methods that improve the quality of a metal in metal castings through the influence of alloying elements on its structure and properties have been considered. These methods are very effective for reducing the tendency of a metal to form a coarse–grained structure. The paper describes optimal techniques for melting special alloys in induction and electric furnaces. A set of rules for the selection of a melting temperature before pouring a metal into the casting forms depending on the dimensions, wall thickness, geometry of castings have been determined. The behavior of new alloys under the conditions of high temperatures, aggressive environments has been studied. It has been established that heat–resistant Cr–Al steels exhibit high heat resistance and wear resistance properties; they 6–8 times surpass Cr–Ni steels in oxidation resistance. The proposed Cr–Mn cast iron processed in an integrated manner with REM (rare earth metals) and Ti is superior to a basic cast iron in conditions of a heavy wear. Numerous industrial trials confirm the usefulness of recommended new casting materials for use under extreme conditions.

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Development of New High-Strength and Heat-Resistant Mg-Zn-Y-X (X=Zr and Ag) Casting Alloys

Materials Science Forum ◽

10.4028/www.scientific.net/msf.783-786.384 ◽

2014 ◽

Vol 783-786 ◽

pp. 384-389 ◽

Cited By ~ 1

Author(s):

Yuichi Ienaga ◽

Kenshi Inoue ◽

Tokuteru Uesugi ◽

Yorinobu Takigawa ◽

Kenji Higashi

Keyword(s):

Room Temperature ◽

Cast Alloy ◽

High Strength ◽

Fatigue Properties ◽

Casting Alloy ◽

Heat Resistant ◽

Casting Alloys ◽

Equiaxed Grains ◽

Zirconium Addition ◽

Current Heat

In order to develop a high strength and heat-resistant magnesium alloy, we focused on controlling microstructure of Mg96Zn2Y2 (at %) casting alloy by the addition of a 4th element. Initially, we investigated the effects of zirconium addition and cooling rate for grain refinement on microstructure and mechanical properties. Consequently, Mg95.8Zn2Y2Zr0.2 casting alloy contains fine equiaxed grains (approx. 0.01 mm), and it exhibits tensile and fatigue properties equivalent to or higher than those of commercial aluminum alloys at high temperature above 473 K. At 523 K, this alloy exhibited a tensile strength of 223 MPa nearly twice that of A4032-T6 alloy used in typical automotive pistons. The Mg95.8Zn2Y2Zr0.2 casting alloy also reveals sufficient ductility and good castability, characteristics not common in current heat-resistant magnesium alloys. Next, we focused on controlling microstructure of Mg96Zn2Y2 casting alloy by the addition of Ag. Mg96Zn2Y2 cast alloy is composed of alpha-Mg phase, long-period stacking ordered phase and Mg3Zn3Y2 phase; on the other hand, Mg-Zn-Y-Ag cast alloy had 4th phase by an addition of Ag. A substantial increase in yield strength at room temperature, without grain refining, was the result.

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