Tungsten Alloy Military of History

From 1965 to 1972, the US Army conducted a parallel development program for the 152mm XM578 cartridge, which was co-developed with the prototype MBT-70 Tank. The XM578 cartridge used a 

tungsten alloy that was slightly denser than the British alloy, consisting of 97.5 percent tungsten and 2.5 percent binder, which had a density of 18.5 gm/cc. In response to the new operational 

requirements, military developers evaluated a succession of metal alloys. Initially, the British government developed a higher density tungsten alloy consisting of 93 percent tungsten and 7 percent binder tungsten alloy (WA). The new WA alloy had a density of 17 gm/cc -- versus 13 gm/cc for tungsten carbide. 

Unfortunately, rising costs and technical problems caused the partners to go their separate ways. Trials began in 1968 and problems resulted in further delays and cost overruns. By 1969 the vehicle cost 5 times what was projected and as a result Germany backed out of the project. The MBT-70 program was finally halted in January 1970. The same fiscal year (1971-72) witnessed the termination of two major weapons procurement programs, one 

for the Cheyenne advanced attack helicopter and the other for the MBT-70 main battle tank. Although Army leaders saw both weapons systems as critical to the Army's long overdue modernization program, they were unable to convince the Department of Defense and Congress of a need for these weapons commensurate with their costs. The joint effort with the Federal Republic of Germany, under which the MBT-70 had been developed, was modified to a co-operative program in the middle of Fiscal Year 1970.