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.

The technique of melting and casting rare earth giant magnetostrictive bars was investigated with super high temperature gradient directional solidification equipment developed by the authors. A number of f73120-mm bars with a smooth appearance were manufactured successfully; bars with different dimensions can be obtained by changing the molds. The results reveal that the fabrication process is available and simple. Under normal melting, the losses of Tb and Dy can be controlled to within 1 and 3%, respectively. The mean composition errors of the rare earth elements Tb and Dy are less than 1.5%. Metallographic examinations reveal that the microstructure is notably dependent on the mold temperature. In addition, the full process from melting and casting to directional solidification can be performed in the same equipment, and investment in facilities for melting and casting is not required.

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.

We have prepared polycrystalline Ca32xEuxCo4O9þd (x=0, 0.15, 0.3 and 0.45) samples using a sol-gel process followed by SPS sintering and investigated the Eu substitution effects on their high-temperature thermoelectric properties. With the Eu substitution, both the electrical resistivity and thermopower increase monotonously. This could be attributed to the decrease of hole concentrations by substitution of trivalent Eu3þ for divalent Ca2þ. The Eu substituted samples (x=0.15; x=0.3) have lower thermal conductivity than Ca3Co4O9þd due to their lower electronic and lattice thermal conductivity. The dimensionless figure of merit ZT reaches 0.3 at 1000 K for the sample of Ca2.7Eu0.3Co4O9+δ.

Ca3−xDyxCo4O9+δ (x=0, 0.15, 0.3 and 0.45) polycrystalline samples have been prepared using a sol-gel process followed by SPS sintering. Their thermoelectric properties have been carefully studied from room temperature to 1000 K. The substitution of Dy for Ca results in increasing of both thermopower and electrical resistivity, which could be attributed to the decreasing of carrier concentrations. The Dy substituted samples (x=0, 0.3) have lower thermal conductivity than Ca3Co4O9+δ due to their lower electronic and lattice thermal conductivities. The dimensionless figure of merit ZT reaches 0.27 at 1000K for the sample of Ca2.7Dy0.3Co4O9+δ.