Main drawback of Be in Ni-Cr alloys

Although beryllium is known to be highly toxic, it is used in some Ni-Cr alloys in concentrations of 1% to 2% by weight (approximately 5.5% to 11% atomic content) to increase the castability of these alloys and lower their melting range. It also tends to form thin adherent oxides that are required to promote atomic bonding of porcelain.  Base metal alloys containing both beryllium and nickel exhibit high beryllium release rates, which may pose a health risk. Beryllium-containing particles that are inhaled and reach the alveoli of the lungs may cause a chronic inflammatory condition called berylliosis.  Berylliosis occurs only in individuals with a hypersensitivity to beryllium and may occur from inhalation of beryllium dusts (from grinding or polishing alloys), salts, or fumes such as those encountered in casting beryllium-containing alloys. Thus, dental lab technicians would presumably be at the highest risk of adverse effects from exposure to beryllium dusts and vapors. Ref: Phillip’s 12th edition page 128.