When Cr + 3.2% Co is field cooled (FC) from 400 K through the Néel temperature K in the 100 Oe measuring field of a SQUID magnetometer, irreversibility of the magnetic susceptibility occurs relative to the zero-field-cooled (ZFC) state, beginning at the irreversibility limiting temperature K. decreases in ternary alloys with up to x = 1% V, but more slowly than , and the relative magnitude of the hysteresis increases. It is believed that a phase transition occurs at , perhaps to a local spin-density-wave state.