Recently, the number of the car increases as the automotive industry develops. Therefore, the reduction of the environmental pollutant exhausted by the cars becomes a serious problem. Especially, the pollutant exhausted by the diesel engine such as NOx and particulate matter (PM) gives the life environment big damages. The generation of these environmental pollutants can be controlled by using magnetostrictive alloy for the control mechanism of the fuel injection system. Technical equipment is necessary for the industrial manufacturing though the single crystal of giant magnetostrictive alloy obtains large magnetostriction. Moreover, it is difficult for the single crystal to fabricate a compact with a complex shape. To obtain the compact of the polycrystal, the new process that mechanical alloying (MA) was combined with a pulsed current sintering(PCS) is reported to be effective. In this study, the effect of chromium addition on the magnetostriction and compressive strength of the (Tb0.5Dy0.5)(Fe1-xCrx)1.8 (x=0-0.2) compacts have been investigated. The powders of (Tb0.5Dy0.5)(Fe1-xCrx)1.8 (x=0-0.2) were synthesized by an MA of the elemental Tb, Dy, Fe and Cr powders using a planetary ball milling for 360 ks, and they were consolidated at 1273 K by PCS. The Cr addition has been very effective to improve compressive strength of the sintered alloys, which is attributed to the formation of ductile Fe-Cr phase. On the other hand, the Cr addition of x=0.2 decreased magnetostriction of the alloys due to an excess amount of Fe-Cr phase. As a result, it has been found that the optimum Cr content is x=0.05 for achieving large magnetostriction and high compressive strength simultaneously.
