Laves phases with their comparably simple crystal structure are very common intermetallic phases and can be formed from element combinations all over the periodic table resulting in a huge number of known examples. Even though this type of phases is known for almost 100 years, and although a lot of information on stability, structure, and properties has accumulated especially during the last about 20 years, systematic evaluation and rationalization of this information in particular as a function of the involved elements is often lacking. It is one of the two main goals of this review to summarize the knowledge for some selected respective topics with a certain focus on non-stoichiometric, i.e., non-ideal Laves phases. The second, central goal of the review is to give a systematic overview about the role of Laves phases in all kinds of materials for functional and structural applications. There is a surprisingly broad range of successful utilization of Laves phases in functional applications comprising Laves phases as hydrogen storage material (Hydraloy), as magneto-mechanical sensors and actuators (Terfenol), or for wear- and corrosion-resistant coatings in corrosive atmospheres and at high temperatures (Tribaloy), to name but a few. Regarding structural applications, there is a renewed interest in using Laves phases for creep-strengthening of high-temperature steels and new respective alloy design concepts were developed and successfully tested. Apart from steels, Laves phases also occur in various other kinds of structural materials sometimes effectively improving properties, but often also acting in a detrimental way.

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Laves phases: a review of their functional and structural applications and an improved fundamental understanding of stability and properties

The effect of microstructure evolution on the mechanical properties of martensite ferritic steel during long-term aging

Study on the nucleation and growth of M23C6 carbides in a 10% Cr martensite ferritic steel after long-term aging

High operating temperatures can have very deleterious effects on the long-term performance of high-Cr, creep-resistant steels used, for example, in the structural components of power plants. For the popular creep-resistant steel X20CrMoV12.1 we analysed the processes of carbide growth using a variety of analytical techniques: transmission electron microscopy (TEM) and diffraction (TED), scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). The evolution of the microstructure after different aging times was the basis for a much better understanding of the boundary-migration processes and the growth of the carbides. We present an explanation as to why some locations are preferential for this growth and using EBSD we were able to define the proper orientational relationship between the carbides and the matrix.

Coarsening behaviour of M23C6 carbides in creep-resistant steel exposed to high temperatures.

The low-cycle fatigue behavior of P92 ferritic-martensitic steel and the corresponding microstructure evolution at 873 K has been extensively studied. The test results of fatigue lifetime are consistent with the Coffin-Manson relationship over a range of controlled total strain amplitudes from 0.15 to 0.6%. The influence of strain amplitude on the fatigue crack initiation and growth has been observed using optical microscopy and scanning electron microscopy. The formation mechanism of secondary cracks is established according to the observation of fracture after fatigue process and there is an intrinsic relationship between striation spacing, current crack length, and strain amplitude. Transmission electron microscopy has been employed to investigate the microstructure evolution after fatigue process. It indicates the interaction between carbides and dislocations together with the formation of cell structure inhibits the cyclic softening. The low-angle sub-boundary elimination in the martensite is mainly caused by the cyclic stress.

Low-Cycle Fatigue Properties of P92 Ferritic-Martensitic Steel at Elevated Temperature

Study on the nucleation and growth of Laves phase in a 10% Cr martensite ferritic steel after long-term aging

The invention discloses a steel ingot feeder head induction heating and electromagnetic stirring device which can be used for heating and heat preservation and electromagnetic stirring for a cast ingot feeder head made of ferrous and nonferrous materials The steel ingot feeder head induction heating and electromagnetic stirring device is characterized in that a plurality of groups of induction coils (5) are vertically placed outside a heat preservation sleeve (2) of a steel ingot feeder head and connected with a three-phase power frequency power cabinet (7) through water-cooled cables, and magnet yokes (10) are evenly distributed outside the plurality of groups of induction coils (5) along the peripheral direction After the steel ingot feeder head induction heating and electromagnetic stirring device is powered on, a magnetic field is formed around the steel ingot feeder head to carry out induction heating on feeder head liquid steel, compensate heat loss of the feeder head in steel ingot solidification, slow solidification process of the feeder head and improve feeding capacity of the feeder head Meanwhile, a metal melt has an electromagnetic stirring effect under the action of the magnetic field, the circulation that liquid metal in the center of a steel ingot moves upwards and liquid metal outside the steel ingot moves outwards is formed, and gas and inclusion in the melt can be discharged beneficially Through the interaction effect of two physical processes, the phenomena of center porosity and center segregation of the steel ingot are reduced, and quality of the steel ingot is improved

Steel ingot feeder head induction heating and electromagnetic stirring device

The utility model discloses an induction heating device for a riser of a steel ingot. The induction heating device for the riser of the steel ingot is applicable to heating and heat preservation of liquid metal at the positions of risers in the process of solidification of ferrous metal steel ingots and non-ferrous metal steel ingots in the vacuum or antivacuum condition. According to the induction heating device for the riser of the steel ingot, an upper set of induction coil (6) and a lower set of induction coil (5) are placed outside a riser heat preservation sleeve (2) in the perpendicular direction, and an alternating magnetic field is used for carrying out induction heating on the liquid metal of the riser to compensate heat loss of the riser in the process of solidification of the steel ingot and to delay the process of solidification of the riser. In the process of induction heating, heating and heat preservation can be carried out on the steel ingots with different sizes through adjustment on the frequency and the power of supply power input by a silicon controlled power supply cabinet (7) to the electromagnetic induction coils (6,5), the feeding capacity of the riser of the steel ingot is improved, the size of the riser is reduced, and the use ratio of the steel ingot is remarkably improved. According to the induction heating device for the riser of the steel ingot, the heating mode belongs to induction heating, heat is from volumetric heat produced by a metal melt body in a permeating layer, and the induction heating device for the riser of the steel ingot has the advantages of being large in heating area, high in heating efficiency, convenient to control and the like.

Induction heating device for riser of steel ingot

The utility model discloses an induction heating and electromagnetic stirring device for a riser of a steel ingot. The induction heating and electromagnetic stirring device for the riser of the steel ingot can be used for heating, heat preservation and electromagnetic stirring of risers of ingots of ferrous metal materials and non-ferrous metal materials. According to the induction heating and electromagnetic stirring device for the riser of the steel ingot, a plurality of sets of induction coils (5) are perpendicularly placed outside a riser heat preservation sleeve (2) of the steel ingot, the induction heating and electromagnetic stirring device is connected with a three-phase power frequency power supply cabinet (7) through water-cooling cables, and magnet yokes (10) are evenly distributed outside the induction coils (5) in the peripheral direction. When a power source is connected, a magnetic field is formed at the periphery of the riser of the steel ingot, induction heating is carried out liquid steel of the riser, heat loss of the riser is compensated in the process of solidification of the steel ingot, the progress of solidification of the riser is delayed, and the feeding capacity of the riser is improved. Meanwhile, a metal melt body plays a role in electromagnetic stirring under the action of the magnetic field, circulation that liquid metal in the center of the steel ingot moves upwards, and the external liquid metal moves downwards is formed, and removal of gas and inclusions in the metal melt body is facilitated. Two physical processes are in interaction, the frequency of the phenomena of center porosity and segregation is avoided, and quality of the steel ingot is improved.

Huang Jing

Papers

Study on the nucleation and growth of Laves phase in a 10% Cr martensite ferritic steel after long-term aging

Steel ingot feeder head induction heating and electromagnetic stirring device

Induction heating device for riser of steel ingot

Induction heating and electromagnetic stirring device for riser head of steel ingot