is added again, i.e., the temperature is raised so the alloy can be smelted to "homogenize" it (1:9). When this occurs, there is little or no further uptake of Zn, because the exposed surface area of Cu available for additional Zn-vapor uptake has been so drastically reduced (1:9). This process and its limitations on Zn-uptake militated against the utilitarian formation of beta or other phases of brass for ten centuries or longer (5:130-34).
Phase Diagram for All Brasses. As depicted in a "phase diagram" for the Cu-Zn system (a plot of temperatures as the ordinate from below freezing to above melting for both metals vs. %-Zn in the alloy as the abscissa), at or below 28%-Zn content, Cu-Zn alloys formed will contain an ?-form of dendritically-cored solid (14:19). The ?-brasses, formed at Zn-contents above 47% Zn, are harder--much harder--than ?-phase brasses and can withstand very little cold working at their quenched, 'room' temperatures (14:20). Alpha brasses also do much better when cold worked and annealed (held at an elevated if moderate temperature for
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