The effects of the Ni and Ga content on the martensitic transformation of Ni-Fe-Ga alloys with composition close to Ni55Fe17.5Ga27.5 were investigated. The DSC results show that the martensitic transformation temperatures increase with Ni addition or Ga depletion. A complete thermoelastic intermartensitic transformation and retransformation in Ni58Fe17.5Ga27.5 alloy in the vicinity of 370K was observed,the hysterisis of martensitic and intermartensitic ransformation are 10.54 and 5.07 K, respectively.

In a super high temperature gradient directional solidification equipment developed by the authors, f7 mm rare earth giant magnetostrictive rods with precise <110> orientations were manufactured successfully without any seed crystal. A dispersion of only 38 exists between the k110l oriented growth direction and the axis of the rod. During the directional solidification process, there exists a certain relationship between the crystal growth morphology and the crystalline orientation degree. The crystallites-orientation degree can be determined conveniently through the observation of the crystal morphology. Under the condition of the temperature gradient of 800K/cm and the withdrawal velocity of 6mm/s|10mm/s, Tb Dy Fe rod with k110l oriented crystals can be obtained when the 0.27 0.73 1.9 solidified part of the rod reaches 20mm. When the length of the solidified part is at least 30mm, the <110> oriented crystallines can grow in a stable way.

Structural evolution of bulk undercooled Ni/11.56 at.% Pb monotectic alloy was investigated systematically by using molten glass denucleating combined with superheating cycling. Within the achieved undercooling range 10/286K, the solidification structures were classified into three categories. When the undercooling was less than 50K, the structures consisted of coarse dendrites and interdendritic lead phase. With the undercooling increasing into the range of 70/232K, the dendrite clusters were refined and fine lead particles separated out from the supersaturated primary dendrite arms because of solute trapping. When the undercooling exceeded 242K, the granular grains formed and fine lead particles homogeneously distributed in the whole sample. The phase selection of high temperature melts was analyzed by adopting steady state nucleation theory. The calculated results shown that undercooled Ni/11.56 at.% Pb monotectic alloy melts solidified in the form of a(Ni) dendrites essentially during the stage of rapid solidification and after recalescence, the interdendritic residual melts solidified in the equilibrium mode. Based on the observation of the solidification structures and the calculated results with BCT dendritic growth model, it was confirmed that the granulation mechanism of the granular grains was owing to the primary dendritic disintegration and subsequent recrystallization.

Effects of the crystal growth velocity on the crystal orientation and the microstructures of the Tb Dy Fe compound have been 0.27 0.73 1.9 investigated in an optical image zone melting furnace. The results indicate that the crystal growth velocity is very important to prepare oriented crystals of Terfenol-D. Without any seed crystals, when the velocity is lower than 5mm/ h, mainly k111l oriented crystals can be obtained. When the velocity is changed between 5mm/h and 15mm/ h, Terfenol-D crystals with k112l orientation or k110l orientation can be obtained. When the velocity is higher than 15mm/h, k113l oriented crystals can be prepared. The microstructures are in agreement with the X-ray diffraction patterns. The shape of the grains is round or that of a polygon. During the preparation of the Terfenol-D oriented crystal in an optical image zone melting furnace, the length of the molten zone, shape of the molten zone and temperature of the molten zone as well as the crystal growth velocity are important to prepare precisely oriented crystals of Terfenol-D. In the optical image zone melting furnace, a low crystal growth velocity can effectively suppress twin formation in Tb Dy Fe compounds. For the 0.27 0.73 1.9 composition of Tb Dy Fe , k111l oriented twinless single crystals or polycrystals can be possibly prepared in the furnace by well 0.27 0.73 1.9 controlling the solidification conditions.