The advantageous thermal stability and construction workability of gussasphalt, a type of asphalt concrete, has drawn increasing attention. To prepare a type of superior gussasphalt concrete using Qingchuan rock asphalt (QRA), a modified gussasphalt binder was prepared with modifiers made up by different dose of styrene-butadiene-styrene, terpene resin, furfural extraction oil and SAW. Then, the rheological properties, microstructure, and thermal stability of gussasphalt binder were studied. The results indicated that the modifier #1 had significant effects on the other indexes but for the ductility, it was less effective in improving the low-temperature performance of the asphalt binder. The low-temperature performance of the binder with modifier #2 was superior compared with that of binder with modifier #1. The binder with 12.5% QRA and 5% modifier #2 can be regarded as an optimal collocation, which had a superior compatibility, high-temperature performance, and comprehensive temperature susceptibility.

The melting of a 201 austenitic stainless steel was conducted in mushy zone for 0, 5, 10, 15 min under nitrogen atmosphere. The effect of the holding time on nitrogen content was investigated. The results showed that with the increase of holding time, the nitrogen content was significantly increased. It was found that the holding in mushy zone could avoid ferrite region during solidification, and facilitate the diffusion of nitrogen from liquid into austenite. Thermodynamic analysis demonstrates that the difference between the chemical potential of nitrogen in liquid and austenite provides the driving force for the nitrogen diffusion. It is concluded that melt holding in mushy zone is an effective way for increasing the nitrogen content in stainless steel, and thus provides a new method for the production of high nitrogen stainless steel.

Ordered porous copper with elongated pores has been fabricated by a continuous unidirectional solidification method in a hydrogen gas atmosphere with high pressure. The porosity of the ordered porous copper is significantly affected by the pressure of hydrogen. A theoretical model is developed to get the relation between the porosity and the processing parameters. The calculated values are in good agreement with the experimental results. Key words: Unidirectional solidification; Ordered porous copper; Porosity; Modeling.

Gas pores growing inside the columnar grains, instead of at grain boundary regions were observed in a lotus type porous copper. It is suggested that the lack of effective nucleation substrate in the pure copper melt makes the nucleation and subsequent growth of gas pores difficult. Therefore the melt must be sufficiently undercooled to provide enough free energy for the nucleation, and as a result the gas saturated melt will transform into a higher energy state of gas pores inside the columnar grains. Keywords: Porous material; Solidification; Gas Pore; Nucleation.

Lotus-type porous copper materials were fabricated by continuous casting technique. The relationship between porosity and external pressure were developed based on the solute mass conservation law. Theoretical values of porosity are in agreement with our experimental results. Results show that porosity decreases when the partial pressure of hydrogen increases for cases of no pressure of argon above melt, while porosity first increases and then decreases as the partial pressure of hydrogen increases for case of nonzero pressure of argon above melt.