Theories LENR much. I stopped on "..angarmonicheskih vibrations" as the most simple. According to her it is necessary to saturate with hydrogen the metal and give an initial jolt (eg temperature variations). So far, according to this theory. The solubility of hydrogen in the nickel increases with increasing temperature, this table (at atmospheric pressure): http://jivisam.ru/uploads/books/tabl.rastv_.vodoroda_.png
(никель == nikel).
A different additives in the form of lithium oxide, and others - such as possible impact.
With pressure problems, my equipment does not allow. Buy the same can not. It seems that it works. It is necessary to continue to experiment.
Seditious thought: Maybe, and nickel is not necessary, and enough iron, heat it and stronger ..?