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Thermal Stability of Amorphous Hydride Mg_(50)Ni_(50)H_(54) and Mg_(30)Ni_(70)H_(45)

Quanmin YANG , Yongquan LEI+ , Changpin CHEN , Jing WU , Qidong WANG , Dept. of Mater. Sci. and Eng. , Zhejiang Univresity , Hangzhou , 310027 , China

材料科学技术(英)

The thermal stability of amorphous ternary hydrides Mg_(50)Ni_(50)H_(54) and Mg_(30)Ni_(70)H_(45) and their corre- sponding amorphous binary alloys Mg_(50)Ni_(50) and Mg_(30)Ni_(70) were studied with X-ray diffraction (XRD) and differential scanning calorimetry(DSC). Samples of the amorphous alloys were prepared by mechanical alloying and the amorphous hydrides were obtained by charging the alloys with gas- eous hydrogen at 3.0 MPa and 423 K. It was found that the amorphous hydrides released most of their hydrogen before the crystallization of the essentially hydrogen depleted amorphous alloy. The crystallization temperature of amorphous Mg_(50)Ni_(50)H_(54) elevated and that of amorphous Mg_(30)Ni_(70)H_(45) did not change in relation to the original binary amorphous alloy. This is very excep- tional for amorphous hydrides. The reason for the effects of hydrogen absorption/desorption on the crystallization of amorphous alloys was discussed.

关键词: amorphous hydride , null , null , null

Effects of Microstructure on the Tensile, Fracture Toughness and Fatigue Behaviour of Gamma Titanium Aluminides

Young- Won (Y-W.) Kim(UES , Inc. , Materials Research Division , 4401 Dayton-Xenia Rd. , Dayton , OH 45432 , USA)(Paper presented at the International Workshop on OrderedIntermetallics 1992 , Hangzhou , China)

材料科学技术(英)

The effects of microstructure on the deformation and fracture behaviour of two-phase TiAl alloys were investjgated under monotonic and cyclical loading conditions, over a range of temperatu res.The tensile behaviour is analyzed for deformation temperatures between RT and 950℃, Fracture resistance behaviour and toughening mechanisms at RT and 800℃ are analyzed. and the inverse relationship botween ductility and toughness is explained using the crack initiation toughness. The preliminary results of load-controlled fatigue behaviour at 800℃ are interpreted using the tensile behaviour because deformation structure and fracture modes are similar under these two loading conditions

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H-plasma In-situ Cleaning and Lattice Damage Elimination

Chenguang GONG+ , Fuchu SHEN , Biguang YE , Jian CHEN , Zhenjiang University , Hangzhou , 310027 , China

材料科学技术(英)

This article discusses the silicon lattice damage induced during H-plasma in-situ cleaning and finds that the substrate temperature, plasma power, processing time, all affect the extent of the distortion of the surface and its curability.

关键词: H-plasma cleaning , null , null , null

Fusion Equation of Metals

HONC Yongyan Zhejiang Institute of Technology , Hangzhou , China.

材料科学技术(英)

An expression of initial slope of melting curve of pure metals was obtained as follows: (dT_m/dP)_o=T_(mo)/c, where c=1.09 (N_(at))~(5/3)z~(-1/3), the unit of c is GPa, N_(at) is the atomic concentra- tion (in 10~(28) m~(-3)), z is the valence, T_(mo) is the melting temperature (in k) of metal under one atmosphere. The calculated results for thirty-one metals agree well with experiments. It has also been proved that by using the free electron model of melting, the fusion equation of metals is Simon equation (T_m/T_(mo))q=1+(p/d). Two parameters q and d, which have to fit with experiments in Simon's empirical equation, now can be predicted theoretically, e.g. for Mg, giving q=1.56, d=7.88GPa, the calculated melting curve in a fairly wide pressure range (0~60GPa) is shown to be close to the experimental one.

关键词: melting curve of metals , null

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