Excess Heat and Influences of Temperature and Atmosphere on the Microstructure of Pd-Ni-Zr Alloy Nanopowders

The Pd-Ni-Zr alloy has been identified as one of the most promising materials for low-energy nuclear reactions (LENR). The simple and efficient fabrication of the Pd-Ni-Zr alloy, in conjunction with systematic investigations into its control factors, significantly advances the progress of LENR. In this study, Pd-Ni-Zr alloy nanopowders with different compositions were prepared by high energy ball milling and subjected to heat treatment including high-temperature vacuum annealing, high-temperature oxidation and deuterium reduction. The grain refinement process of Pd-Ni-Zr alloy nanopowder was explored based on different ball milling times. The deuterium reduction of Pd-Ni-Zr samples prepared under different ball-milling conditions reached a minimum of 27 nm, accompanied by a high density of defects including dislocations, interfaces, and amorphous structure. From the results of scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD), the influence of temperature and atmosphere on the morphology, phase structure, and crystallinity of Pd-Ni-Zr alloy was revealed. Excess heat of Pd-Ni-Zr alloy nanopowder in D2 was assessed with a high-precision Seebeck calorimeter. Results demonstrate that both the activation treatment (involving high-temperature oxidation and deuterium reduction) and the stepwise variation of reaction temperature are critical factors for enhancing the excess heat of Pd-Ni-Zr alloy. Excess power of 0.6 W (or 120 W/kg of the sample) was obtained with the optimized Pd-Ni-Zr alloy samples.