A brass that has more zinc and is stronger than alpha brass; used in making castings and hot-worked products WordNet 3.0 & Open English WordNet

Muntz metal is an alpha-beta brass alloy composed of approximately 60% copper, 40% zinc and a trace of iron. It is named after George Fredrick Muntz, a metal-roller of Birmingham, England, who commercialised the alloy following his patent of 1832. Wikipedia

A form of brass with about 60% copper, 40% zinc, and a trace of iron. Wiktionary