Metallic materials for structural applications beyond nickel-based superalloys

Abstract

This paper reviews our current research activities on developing new multiphase metallic materials for structural applications with a temperature capability beyond 1,200ºC. Two promising material systems have been chosen: fi rst, alloys in the system Mo-Si-B which have demonstrated potential due to their high melting point of around 2,000ºC and due to the formation of a protecting borosilicate glass layer on the surface at temperatures exceeding 900ºC; and second, novel Co-Re-based alloys which have been chosen as a model system for complete miscibility between the elements cobalt and rhenium, offering the possibility of continuous increases of the melting point of the alloy through rhenium additions.

Similarities and Differences in Mechanical Alloying Processes of V-Si-B and Mo-Si-B Powders

“…Due to the solubility of Fe in the V and Mo lattice, respectively, these impurities are dissolved in the solid solution phases. 4 The microstructural evolution in both types of alloys follows the same trend: During the first 2 h of milling, typical layered (lamellar) structures form due to high deformation (flattening) and welding of the ductile elements V or Mo, respectively, and fracturing of the brittle components. Longer milling or an increased rotational speed of the ball mill leads to the decrease of the lamellar spacing and the homogenization until a supersaturated solid solution phase forms.…”

“…Secondly, by using lightweight materials with similar mechanical properties compared to conventional materials, the reduction of mass inertia will also affect the efficiency of the process. Amongst other refractory metal-based alloys several new molybdenum and vanadium alloys, which follow the approaches described above, provide excellent mechanical properties in a wide temperature range, offering promising possibilities in terms of various high temperature applications [3][4][5][6][7][8][9].…”

Powder Metallurgical Production of Innovative High-Temperature Materials

“…Zusammenfassende Darstellungen über Herstellungsverfahren und den daraus resultierenden Eigenschaften der RM-Silizidlegierungen finden sich in [26][27][28]. [30].…”

Design Considerations and Strengthening Mechanisms in Developing Co-Re-Based Alloys for Applications at + 100°C above Ni-Superalloys

“…Improving the temperature capability of superalloys, which are already used very close to their melting range (1300° -1400°C) is limited by the possibility to raise further their melting point. Many efforts are being made worldwide for developing new alloy systems to supplement Ni-base superalloys in future [1]. A novel concept of using Co-Re-base alloys was introduced by us to meet this demand [2].…”