Development of thermodynamic and kinetic databases in micro-soldering alloy systems and their applications

AbstractRecent progress in the development of thermodynamic and kinetic databases of micro-soldering alloys, which were constructed within the framework of the Thermo-Calc and DICTRA software, was presented. Especially, a thermodynamic tool, ADAMIS (alloy database for micro-solders) was developed by combining the thermodynamic databases of micro-solders with Pandat, a multi-component phase diagram calculation software program. ADAMIS contains 11 elements, namely, Ag, Al, Au, Bi, Cu, In, Ni, Sb, Sn, Zn and Pb, and can handle all combinations of these elements in the whole composition range. The obtained thermodynamic and kinetic databases can not only provide much valuable thermodynamic information such as phase equilibria and phase fraction, but also shows the kinetics and the evolution of microstructures when they are combined with some appropriate software programs and models, such as the phase field method and ADSTEFAN software. From the viewpoints of computational thermodynamics and kinetics, some technical examples were given to demonstrate the great utility of these databases for the applications in the development of micro-soldering materials. These databases are expected to be powerful tools for the development of micro-solders and Cu substrate materials, as well as for promoting the understanding of interfacial phenomena and microstructure evolution between solders and substrates in electronic packaging technology

Magnetocaloric Effects in Metamagnetic Shape Memory Alloys

Recently, metamagnetic shape memory alloys have attracted much attention as candidates for the rare-earth free magnetic refrigerants. These materials undergo the martensitic transformation (MT) at around room temperature accompanied by a significant entropy change. The application of the magnetic field at the low-temperature martensitic phase realizes the magnetic field-induced martensitic transformation (MFIMT). Through the MFIMT, the materials show an unconventional magnetocaloric effect (MCE), which is called inverse magnetocaloric effect (IMCE). In this chapter, the direct measurement system of MCE in pulsed-high-magnetic fields is introduced. With taking the advantage of the fast field-sweep rate of pulsed field, adiabatic measurements of MCE are carried out at various temperatures. Using this technique, the IMCEs of the metamagnetic shape memory alloys NiCoMnIn and NiCoMnGa are directly measured as adiabatic temperature changes in pulsed fields. From the experimental data of MCE for NiCoMnIn, the entropy of spin system in the austenite phase is estimated through a simple mean-field model. By the combination of MCE, magnetization and specific heat measurements, the electronic, lattice and magnetic contributions to the IMCE are individually evaluated. The result for NiCoMnIn demonstrates that lattice entropy plays the dominant role for IMCE in this material