Over the years, going all the way back to Pons and Fleishmann, there has been clear and specific info on active host metals - to wit: palladium-silver alloy works well in cold fusion and pure Pd does not.
Fleischmann said of "Type A" : "Look at the data from Miles. What does it tell you? When Uncle Martin gives you palladium, it works. When you get the palladium from somewhere else, it doesn't work! Why don't people pay attention to that ?" For one thing (as to why this information has been ignored), there is little coherent theory why the alloy (Johnson Matthey - type A) should work, while pure palladium does not work as well ... other than it resists cracking (aka hydrogen embrittlement) and as JM says that is exactly why they developed it in the first place (since pure palladium cracks when fully loaded). Fast forward 30 years. Here is an overlooked and interesting report about a palladium silver alloy developed at CalTech a few years back, in the form of glassy metal. It is much, much stronger the normal Type A. In fact, this could be the strongest metal alloy every developed for any use. Curiously, it is mostly palladium with some silver in the form of a glassy metal (spin cast). This work was done by Demetriou et al, at Keck Engineering Laboratories, California Institute of Technology https://www.caltech.edu/about/news/caltech-led-team-creates-damage-tolerant-metallic-glass-1667https://www.ncbi.nlm.nih.gov/pubmed/21217693 Worth investigating further in LENR ? I doubt that the folks at CalTech tried it for that use. Maybe it is worth a try. Being an exceptionally strong alloy does not necessarily mean that it will also resist hydrogen embrittlement but it could be the key to success. Note: Ahern had moderate success with spin cast palladium (with nickel). It could well be the case that getting palladium into the glassy metal structure makes a big difference when loaded with hydrogen ... who knows? It is also possible that it will not load at all. Abstract of report from Nature Owing to a lack of microstructure, glassy materials are inherently strong but brittle, and often demonstrate extreme sensitivity to flaws. Accordingly, their macroscopic failure is often not initiated by plastic yielding, and almost always terminated by brittle fracture. Unlike conventional brittle glasses, metallic glasses are generally capable of limited plastic yielding by shear-band sliding in the presence of a flaw, and thus exhibit toughness-strength relationships that lie between those of brittle ceramics and marginally tough metals. Here, a bulk glassy palladium alloy is introduced, demonstrating an unusual capacity for shielding an opening crack accommodated by an extensive shear-band sliding process, which promotes a fracture toughness comparable to those of the toughest materials known. This result demonstrates that the combination of toughness and strength (that is, damage tolerance) accessible to amorphous materials extends beyond the benchmark ranges established by the toughest and strongest materials known, thereby pushing the envelope of damage tolerance accessible to a structural metal.
