W. Ma’s scientific contributions

Microstructure and mechanical properties of Zr64+xCu26-xAl10 bulk amorphous alloys and composites were studied. Effect of overheated level on mechanical properties of bulk amorphous composites was also investigated. The relationship between microstructure and mechanical properties was discussed. The results showed that Zr60Cu30Al10 had good thermal stability and the best glass forming ability in the alloy system, of which ΔTx, Trg and γ were 69 K, 0.573 and 0.402, respectively. With the decrease of Cu content, the glass forming ability decreased. Nanocrystalline with different sizes precipitated on the amorphous matrix of Zr64Cu26Al10 alloy. And the presence of nanocrystals could effectively toughen the glass matrix, and hinder the atomic motion in the shear zone to narrow the shear band, thus strengthening the matrix. The fracture strength and plastic strain of Zr64Cu26Al10 alloy were 1610 MPa and 6.34%, respectively. When x=4, 8, 12, crystal phase CuZr2, ZrCu and Cu10Zr7 gradually precipitated in the alloys. And the mechanical properties of the composites depended on the combination of the brittle phases and the toughening phases. The increase of overheated level would promote the formation of amorphous and enhance the strength, thus improving the mechanical properties. © Editorial Office of Chinese Journal of Rare Metals. All right reserved.

Ti-Ni-based amorphous composite samples (Ti0.5Ni0.5)100-xCux with different Cu contents but the same diameter which has been prepared by the copper mold suction casting. The effect of the Cu contents (x=0, 10, 15, 20, 25, 30, 35, 40, at%) on the microstructures and mechanical properties of the amorphous composites was studied. Results show that both fracture strength and plastic strain of the alloy are very high when the copper content is x=20. Meanwhile the alloy exhibits the best comprehensive properties. As the x value increases, the glass forming ability of (Ti0.5Ni0.5)100-xCux alloy shows a waveform change from increasing to decreasing and then to increasing, but following an overall trend towards decreasing. The plasticity of Ti-Ni-based amorphous materials can be improved by adding Cu element in modest quantities (x≈25) to the Ti-Ni-based composites; however, adding more Cu (i.e., x>30) neither can improve the amorphous forming ability nor can enhance its strength. When x=15, the alloy has the highest breaking strength of 2440 MPa while gets the higher yield strength of 1471 MPa causing 17.15% plastic strain. The data are pretty high with respect to other amorphous systems or other alloy systems with memory of their shapes. When x=25, there is a certain increase in the alloy plastic strain with 21.35% plastic deformation. Copyright © 2017, Northwest Institute for Nonferrous Metal Research. Published by Elsevier BV. All rights reserved.