No abstract

No abstract

No abstract

Summary Metal and alloy phase change materials (PCMs) have played an important role in solar energy storage because of their high thermal storage density and thermal conductivity. However, metals and their alloys, especially Mg alloys, are easily oxidized at high temperatures. In order to overcome this shortcoming, we studied the high‐temperature oxidation performance of phase change heat storage alloys. This research investigated and discussed the effect of adding rare earth element yttrium on the high‐temperature antioxidant process in Mg‐based phase change heat storage alloys in detail. In this research, by adding different contents of Y on the basis of Mg‐Ni‐Zn alloys, the cyclic oxidation kinetics and thermodynamics, oxidation products, oxide layer morphology and structure of Mg‐Ni‐Zn‐Y alloys were investigated. The results indicate that the oxidized Mg‐Ni‐Zn‐Y thermal storage alloys are mainly composed of Mg2Ni, ZnO, Y2O3, MgO, and its eutectic structure. The addition amount of Y is positively correlated with the phase transition temperature. The oxidation of Y to Y2O3 segregates on the grain boundaries, hinders the diffusion process of Magnesium ions, Zinc ions, Nickel ions, and Oxygen ions in the oxide film, and replaces the oxidized Mg and Zn elements, which changes the oxidation mechanism and reduces the oxidation of the alloy. And this research provides a theoretical basis for the application of Mg‐based alloy phase change heat storage materials.

Nanosilver pastes have been regarded as the most promising die-attach materials for high-temperature and high-power applications due to their advantages such as excellent thermal conductivity, electrical conductivity, high temperature resistance, and good shear strength. However, the common hot pressing sintering process for nanosilver pastes has the limitations of long sintering time and complicated sintering processes. Thus, laser sintering has been proposed as a rapid sintering method that attracts increasing interest due to its advantages of high energy density, fast temperature rise, easy densification, etc. In this review, the recent advances in laser sintering processes were summarized, including pressure laser sintering, backside sintering, and hybrid bimodal laser sintering. The effects of various laser sintering process parameters on joint performance, such as laser power, sintering pressure, irradiation time, and defocusing amount, were further discussed. The rapid sintering mechanism of laser sintering silver nanoparticles(AgNPs) was revealed, while microscopic explanations need to be further explored. This review provided ideas and methods for subsequent researchers to develop rapid sintering methods for power electronic packaging.