An Al-Si alloy surface was plasma sprayed with a Ni-Cr-B-Si coating. This coating was remelted by a 5kW CO2 laser, and the resulting microstructure was characterized by both scanning and transmission electron microscopy. Both crystalline and amorphous structures were observed to coexist in the remelted layer. Heat resulting from laser scanning precipitated some NisAl in the amorphous region. A distribution in NisAl precipitate size, from nanometer to submicrometer, was observed. Microhardness in the amorphous region measured to I-IV 1235, which is four times as hard as the untreated plasma-sprayed zone.

Since the shape memory effect (SME) in Fe-Mn-Si alloy was observed [1], much research has beendone on this kind of shape memory alloy (SMA) because of its particularly good one-way SME and lowcost [2,3]. With the addition of Cr and Ni, it is possible to reach a good corrosion resislance [4],whichconfers to this type of alloy a future use in industry. But compared with TiNt and Cu-based shapememory alloys, the incompleteness of shape recovery and less reversible strain are the main disadvan-tages of this kind of alloy. Yang et al. 15] reported that the fully reversible strain was less than 2% andonly 4.5% of the nel reversible strain could be obtained under lhe prestrain of 8c). In our present work,by adding Ce, Ti and N, the SME has been improved. By adding Ce, the tully reversible strain is over3% and 5% of the net reversible strain can be obtained in the case of 6.3%, prestrain. The paper is mainly concentrated on the inl]uence of these three elemenls) li the SME ofFe-Mn-Si-Cr-Ni alloys.

Using a 5-kW CO2 laser, a Ni-Cr-Al plasma coating on Al-Si alloy surface was remelted. The microstructure of the clad zonewas analysed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that someamorphous structures and crystallites exist in the laser-clad Ni-Cr-Al coating. The annealing treatment was used at 520

A mixing microstructure containing Ni-based amorphous structures was observed by TEM in the laser clad zones. As the uniformity of chemical composition and temperature is poor in the laser cladding, the amorphous structure with some Ni3Al crystals coexists in the cladding. The microhardness of the mixing amorphous structure is HV 600～800, which is lower than that of crystal phases in the coating. Differential thermal analysis (DTA) shows that Ni-based amorphous structure exhibits a higher initial crystallizing temperature (about 588℃), which is slightly higher than that of the eutectic temperature of Al-Si alloy. The wear test results indicate that there are some amorphous structures in the laser clad coating, which reduces the peeling of the granular phases from matrix, and improves the wear resistance.

Different Mocontents have been added into traditional Finemet alloy to form Fe73.5Cu1Nb3-x Mo xSi13B9.5(x=0～3) alloys. The change in DC and AC magnetic properties with Mo for Nb substitution was investigated. The re-sults show that, with adding Mo, although the DC relative permeability decreases and the coercive force increases slightly,the saturation flux density BS can be increased, and the core loss of the alloy can be decreased. The AC permeability ofsamples contained Mo is higher than that of alloy without Mo content. Fe73.5Cu1Nb1Mo2Si13B9.5 alloy has the highest sat-uration flux density BS. Fe73.5Cu1Nb2Mo1Si13B9.5 alloy has the best frequency dependence on the AC permeability andcore loss.