The Zr55Al10Ni5Cu30 bulk metallic glass plate were successfully welded to crystalline aluminum plates by using a friction stir welding (FSW) method. The welded zone was examined. No defects, cracks or pores were observed and no other crystalline phases except for aluminum were found in the welded joint. The strength of the joint is higher than that of aluminum. The glassy phase in the stir zone keeps the amorphous state, showing a successful welding. The storage modulus softens over the glass transition. And the weldability was discussed according to this phenomena.
Zuoxiang QinCuihong LiHaifeng ZhangZhongguang WangZhuangqi HuZhiqiang Liu
An analytic method is proposed to calculate the formation enthalpy directly from empirical n-body potential and applied to the binary and ternary systems consisting of the refractory metals Mo, Nb, Ta and W. It turns out that the calculated enthalpies are in overall agreement with experimental observations and some other theoretical calculations. Interestingly, it shows that the formation enthalpies of the ternary systems are significantly affected by those of the constituent binary systems.
DAI Ye, LI JiaHao, CHE XingLai & LIU BaiXin Advanced Materials Laboratory, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.
The self-consistent electronic structure calculations were carried out with the accurate frozen-core full-potential projector augmented-wave method on 13 Ni-Pt intermetallic compounds of simple crystalline structures,i.e. A15,D019,D03 and L12 Ni3Pt and NiPt3,and α-NiAs,B1,B2,L2a,and L10 NiPt. The calculations reveal that the L12 Ni3Pt,L10 NiPt and L12 NiPt3 are energetically more stable than their respective competitive structures,indicating that the three structures may be formed in some appropriate conditions. The obtained results match well with the experimental observation or other theory predictions. It is found that there is hybridization between Ni 3d and Pt 5d states,which may significantly affect the structural stability and magnetism of metastable Ni-Pt intermetallic compounds.
Low-cost TiZr-base bulk metallic glasses(BMGs)(Ti36.1Zr33.2Ni5.8Be24.9)100-xCux(x=5,7 and 9) with a maximum size of over 50 mm in diameter were developed by optimizing the alloy composition.The idea is initiated by selecting a particular microstructure comprising primary β-Ti dendrite and amorphous phase.Afterwards,based on this composition of amorphous phase,a class of TiZr-base bulk metallic glasses was designed step by step to reach the optimum composition range.The glass transition temperature(Tg),initial crystallization temperature(Tx) and width of supercooled region(△T) of(Ti36.1Zr33.2Ni5.8Be24.9)91Cu9 BMG are 611,655 and 44 K,respectively.The(Ti36.1Zr33.2Ni5.8Be24.9)91Cu9 BMG exhibits low density of 5.541 g·cm-3 and high compressive fracture strength of 1800 MPa,which promises the potential application as structural materials.
M. Q. Tang H.F. Zhang Z. W. Zhu H.M. Fu A.M. Wang H. Li Z.Q. Hu
