A new technology for high throughput preparation of large-scale bulk materials—screw gradient continuous casting technology

Jingyuan Li*, Mingfan Qi, Shang Dai

University of Science and Technology Beijing, Beijing, 100083, China

EXTENDED ABSTRACT: High throughput experiment is an important means to speed up the development of new materials. In order to meet the requirements of large sample size for tensile strength, elongation, corrosion resistance and other performance tests, it is necessary to prepare block samples with three dimensions above centimeter level. Based on this, A new high-throughput preparation technology, screw gradient continuous caster has been developed. Long rod samples with chemical composition gradient can be prepared via this novel technology. The preparation process is to gradually feed a variety of raw material particles into the melting cavity through an automatically adjusted feeder. A screw rod close to the inner wall of cavity is employed so that the mixed materials flows down along the screw gradually; Finally, it is pulled out after solidification in the bottom of cavity. According to the feeding speed and division of screw, the composition gradient can be obtained. More than 50 kinds of aluminum, magnesium or zinc alloys has been prepared by this technology. Furthermore, welding of glass and brass, particle reinforced aluminum alloy samples have been carried out. The diameter and length of the prepared rod samples can reach 3cm and 60cm, respectively. This paper introduces the preparation of Mg-2Zn-xSn ternary biomedical magnesium alloy and 7-series Al-Zn-Mg-Cu aluminum alloy, the high-throughput characterization of sample bars and the establishment of the genetic relationship between composition, microstructure and properties of materials. Opa-100 metal in-situ analyzer and microbeam X-ray fluorescence in-situ statistical analysis system are used to characterize the chemical composition distribution of gradient bar, and the hardness distribution of gradient bar was characterized by in-situ continuous indentation high-throughput hardness tester. Moreover, high-throughput detection and rapid screening of related properties of alloys with different components were carried out by using conventional microhardness tester, conductivity analyzer, spalling corrosion test and multi-channel electrochemical impedance analysis. The results show that the composition, microstructure and properties of high-throughput bar are consistent with the design. Base on the present study, it can be concluded that the high-throughput preparation technology of screwl gradient continuous casting has the following characteristics: 1) the composition, microstructure and properties can show continuous or span gradient distribution; 2) It can prepare large-size samples above centimeter level, which can meet all routine performance test requirements; 3) By melting and casting, the microstructure and properties can be enlarged to the actual large-scale production process; 4) The number of components, variation range and gradient can be set arbitrarily; 5) It is very suitable for high-throughput screening of corrosion resistance and degradability.