Os sais de Berílio na verdade são Berilatos (Beryllates). Beryllides são compostos intermetálicos entre Berílio e outros metais. Não encontrei tradução e, embora beriletos fosse o caminho natural, realmente o Google não registra nenhuma ocorrência para a palavra. Eu utilizaria "Compostos intermetálicos de Berílio" se o contexto permitisse.

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"Most metals form very brittle intermetallic compounds with
beryllium. This and the low solubility of most elements in solid
beryllium are the reasons that beryllium-rich alloys have not
played a significant role"

"Also, some intermetallic compounds of beryllium, particularly the beryllides of niobium, tantalum, titanium, vanadium, and the borides of beryllium are being considered for use as structural materials for space vehicles (Stokinger, 1981). "

"Cationic beryllium salts are hydrolysed in water and react to form insoluble hydroxides or hydrated complexes at pH values in the range of 5 - 8, and beryllates, above pH 8"
(http://www.inchem.org/documents/ehc/ehc/ehc106.htm)

"beryllides

"Também são ligas endurecíveis por precipitação, porém, ao contrário das ligas Cu-Be de alto teor, nas ligas de baixo teor os precipitados endurecedores são compostos intermetálicos de cobalto e berílio ou de níquel e berílio."
(http://www.infomet.com.br/cu_capitulo09.php)

A group of intermetallic compounds of potential interest as special ceramics. Cell dimensions and types of structure have been reported for the beryllides of titanium, vanadium, chromium, zirconium, niobium, molybdenum, hafnium, and tantalum." (Dictionary of Mining, Mineral, and Related Terms: http://www.maden.hacettepe.edu.tr/dmmrt/index.html)