The Effect of Rapid Solidification on Microstructure and Corrosion of Advanced Biomaterial Co-Cr-Mo-C Alloy

In this research, the microstructure and corrosion properties of rapidly solidified Co-Cr-Mo-C alloy as an advanced biomaterial alloy were studied. The use of rapid solidification casting method represents significant changes in not only the amount of formed e-HCP phase, which is strongly influenced by rapid solidification, but also in electrochemical behavior and solidified structure. In this research, rapid solidified Co-Cr-Mo-C alloy is studied using OM, SEM, EDS, XRD, and dynamic potentiostate. Co-alloy ingots were melted into an induction furnace filled by argon gas and casted into a V-shape sand and chill copper molds to prepare rapid solidified samples and its properties were measured in different cooling rates. The microstructure examination demonstrating the structure of alloy is mainly consist of columnar dendritic structure with the distribution of carbides within primary and secondary dendrites arms and finer dendritic structure along with modified carbide distribution will be achieved by rapid solidification. This structure will improve alloy’s corrosion behavior and reduces its corrosion rate when it is tested in Ringer’s solution as an electrolyte.

Differential Thermal Analysis of Complex Alloyed Brass

Copper alloys are widely used in mechanical engineering. In the article it is shown that the requirements of consumers to properties of alloys are constantly increasing. Complex alloyed brasses have a high wear resistance and corrosion resistance. The wear resistance is a basic property of an alloy. This characteristic determines the operating life of parts working in the wear conditions. The wear resistance is supported by phase composition of alloy, uniformity of distribution of phase in the structure of alloy, their volume fraction, their morphology and their dimensions. At present time the technology of continuous casting of ingots of alloys Cu59Zn34.6Mn3.5Al2.5Fe0.5Ni0.4, Cu70Zn13Mn7Al5Fe2Si2Pb1, Cu58Zn36Mn2Pb2Si1Al1 and Cu58Zn35Mn3Si1.5Ni1.5Pb1 is developed. However, the need to use new alloys for manufacturing of critical parts requires the development of technology for their production, taking into account the composition of alloy and the features of formation of structure. Therefore, it is necessary to establish well-founded technological parameters of melting and casting of ingots of complex alloyed brass Cu62Zn31.6Mn3Al2Si0.8Ni0.4Cr0.2. For determination of temperatures of phase transformations in the structure of alloy, the differential thermal analysis was carried out. Liquidus and solidus temperatures of alloy were determined. The crystallization range of alloy was established. This brass in a solid state undergoes two phase transformations. The temperature of the first phase transformation is 750 oC. The temperature of the second phase transformation is 515 oC. The obtained experimental data make it possible to describe the proposed mechanism of phase transformations in alloy Cu62Zn31.6Mn3Al2Si0.8Ni0.4Cr0.2 during crystallization and following cooling.

Refinement Mechanism of Solidification Structure of Au-20Sn Eutectic Alloy by Different Solidification Techniques

Au-20Sn (mass fraction) eutectic alloy is a key lead-free solder material for high reliability microelectronics and optoelectronics packaging. The refinement of initial solidification structure can improved the processing performance of Au-20Sn alloy. This paper reported the research progresses on refining solidification structure of Au-20Sn alloy in our research group. The results indicated that the solidification structure of alloy can be effectively refined by rapid solidification with the increasing of cooling rate. The solidification structure can also be refined by incubated nucleation treatment with Au or Sn or by proper melt temperature treatment. The refinement mechanisms of solidification structure by the three types of solidification methods were thoroughly discussed.

Crystallization of metals in the ultrasonic field

In the manuscript process of crystallization of metals at ultrasonic influence is considered. The known models of crystallization under the influence of ultrasound are investigated. By means of calculations influence of parameters of ultrasonic influence and characteristics of crystals of metal on the received structure of alloy is established. The corresponding mathematical model of ultrasonic crushing of particles and their agglomerates in metal fusion is offered. It is determined the threshold mode of ultrasonic influence on fusion at which almost monodisperse distribution of particles by the sizes is reached.