ABSTRACT
Titanium alloys are mostly used in aircraft and missile structures where the strength-weight ratio and high temperature resistance are important. The most common of the alloys suitable for diaphragms is titanium alloy Ti-6A1-4V. Low weight, economy, and fabricability favor aluminum alloys over all other metals; however, its use for diaphragm material is somewhat limited. Aluminum alloy 7075-T-6, usually used in instrument applications, is solution-treated and artificially aged to develop maximum strength. Compared with other aluminum alloys, alloy 7075 is attacked by industrial and marine atmospheres; generally it is less corrosion-resistant than other wrought aluminum alloys. Of special interest to diaphragm designers are the metal platinum and its alloys, especially the platinum-palladium alloys. Platinum itself is resistant to most reducing or oxidizing acids in all concentrations but is attacked by aqua regia. The platinum-palladium alloys containing less than 25% palladium are used in place of platinum in many chemical mediums.
