Internal friction measurements on binary and ternary α-phase alloys of Pd with hydrogen and boron have been performed with a torsion pendulum and by observing the cttenuation of ultrasonic pulses. A pronounced dampin...Internal friction measurements on binary and ternary α-phase alloys of Pd with hydrogen and boron have been performed with a torsion pendulum and by observing the cttenuation of ultrasonic pulses. A pronounced damping maximum of binary Pd-B alloys at 220K and measuring frequencies of about 4Hz could not be established at a frequency of 15MH. Ternary Pd-B-H alloys show an additional damping maximum besides the hydrogen Zener effect, which is interpreted in terms of a changed jump frequency of hydrogen in the neighborhood of boron atoms.展开更多
Ultra-high strength alloys with good ductility are ideal materials for lightweight structural application in various industries. However, improving the strength of alloys frequently results in a reduction in ductility...Ultra-high strength alloys with good ductility are ideal materials for lightweight structural application in various industries. However, improving the strength of alloys frequently results in a reduction in ductility, which is known as the strength-ductility trade-off in metallic materials. Current alloy design strategies for improving the ductility of ultra-high strength alloys mainly focus on the selection of alloy composition （atomic length scale） or manipulating ultra-fine and nano-grained microstructure （grain length scale）. The intermediate length scale between atomic and grain scales is the dislocation length scale. A new alloy design concept based on such dislocation length scale, namely dislocation engineering, is illustrated in the present work. This dislocation engineering concept has been successfully substantiated by the design and fabrication of a deformed and partitioned （D＆P） steel with a yield strength of 2,2 GPa and an uniform elongation of 16%. In this D＆P steel, high dislocation density can not only increase strength but also improve ductility. High dislocation density is mainly responsible for the improved yield strength through dislocation forest hardening, whilst the improved ductility is achieved by the glide of intensive mobile dislocations and well-controlled transformation-induced plasticity （TRIP） effect, both of which are governed by the high dislocation density resulting from warm rolling and martensitic transformation during cold rolling. In addition, the present work proposes for the first time to apply such dislocation engineering concept to the quenching and partitioning （Q＆P） steel by incorporating a warm rolling process prior to the quenching step, with an aim to improve simultaneously the strength and ductility of the Q＆P steel. It is believed that dislocation engineering provides a new promising alloy design strategy for producing novel strong and ductile alloys.展开更多
文摘Internal friction measurements on binary and ternary α-phase alloys of Pd with hydrogen and boron have been performed with a torsion pendulum and by observing the cttenuation of ultrasonic pulses. A pronounced damping maximum of binary Pd-B alloys at 220K and measuring frequencies of about 4Hz could not be established at a frequency of 15MH. Ternary Pd-B-H alloys show an additional damping maximum besides the hydrogen Zener effect, which is interpreted in terms of a changed jump frequency of hydrogen in the neighborhood of boron atoms.
基金the support from Research Grants Council of Hong Kong (Grants No. 17203014, HKU712713E and 17255016)the National Natural Science Foundation of China (Grant No. U1560204)
文摘Ultra-high strength alloys with good ductility are ideal materials for lightweight structural application in various industries. However, improving the strength of alloys frequently results in a reduction in ductility, which is known as the strength-ductility trade-off in metallic materials. Current alloy design strategies for improving the ductility of ultra-high strength alloys mainly focus on the selection of alloy composition （atomic length scale） or manipulating ultra-fine and nano-grained microstructure （grain length scale）. The intermediate length scale between atomic and grain scales is the dislocation length scale. A new alloy design concept based on such dislocation length scale, namely dislocation engineering, is illustrated in the present work. This dislocation engineering concept has been successfully substantiated by the design and fabrication of a deformed and partitioned （D＆P） steel with a yield strength of 2,2 GPa and an uniform elongation of 16%. In this D＆P steel, high dislocation density can not only increase strength but also improve ductility. High dislocation density is mainly responsible for the improved yield strength through dislocation forest hardening, whilst the improved ductility is achieved by the glide of intensive mobile dislocations and well-controlled transformation-induced plasticity （TRIP） effect, both of which are governed by the high dislocation density resulting from warm rolling and martensitic transformation during cold rolling. In addition, the present work proposes for the first time to apply such dislocation engineering concept to the quenching and partitioning （Q＆P） steel by incorporating a warm rolling process prior to the quenching step, with an aim to improve simultaneously the strength and ductility of the Q＆P steel. It is believed that dislocation engineering provides a new promising alloy design strategy for producing novel strong and ductile alloys.
