The high-temperature tensile behavior of laser welded Ti-22Al-25Nb (at%) joints was investigated at 500,650,800,and 1 000 ℃.The temperatures for tensile tests were selected according to the phase transformation seque...The high-temperature tensile behavior of laser welded Ti-22Al-25Nb (at%) joints was investigated at 500,650,800,and 1 000 ℃.The temperatures for tensile tests were selected according to the phase transformation sequence of Ti2AlNb-based alloys.At temperatures lower than the B2+O phase field (500 ℃) and higher than the B2+O phase field (1 000 ℃),the joints fracture in the base metal in ductile fracture mode.By contrast,the joints exhibit obvious high-temperature brittleness in the B2+O phase field (650 °C and 800 ℃).Heat treatments were conducted with respect to the thermal history of tensile specimens.Intergranular microcracks along the grain boundary of B2 phase are found in the fusion zone after the heat treatments at 650 ℃ and 800 ℃.The high-temperature brittleness at 650 ℃ and 800 ℃ is attributed to the B2→O transformation along the grain boundary.The stress concentration caused by the volume change of B2→O transformation also contributes to the high-temperature brittleness of laser welded Ti-22Al-25Nb joints.展开更多
质量控制经历了检验质量控制、统计质量控制和全面质量控制3个阶段。为实现全面质量控制,Juran提出质量源于设计(Quality by Design,QbD),将质量的概念扩展到产品质量活动的各个领域和环节。中药全过程质量控制与质量源于设计等全面质...质量控制经历了检验质量控制、统计质量控制和全面质量控制3个阶段。为实现全面质量控制,Juran提出质量源于设计(Quality by Design,QbD),将质量的概念扩展到产品质量活动的各个领域和环节。中药全过程质量控制与质量源于设计等全面质量控制理念的内涵具有内在一致性,为QbD在中药研发和生产中的应用奠定了良好基础。本文提出并阐释了中药全过程质量控制的2个维度,即从研发到生产的产品生命周期维度和从原料到产品的中药产业链维度。总结了中药全过程质量控制在中药材种植加工过程、中药制剂生产过程和中药产品流通过程的应用。展开更多
基金Funded by the National Natural Science Foundation of China(Nos.51804097 and 51879089)the Fundamental Research Funds for the Central Universities of China(No.B200202219)+2 种基金the Changzhou Sci&Tech Program(No.CJ20190049)the State Key Lab of Advanced Welding and JoiningHarbin Institute of Technology(No.AWJ-19M16)。
文摘The high-temperature tensile behavior of laser welded Ti-22Al-25Nb (at%) joints was investigated at 500,650,800,and 1 000 ℃.The temperatures for tensile tests were selected according to the phase transformation sequence of Ti2AlNb-based alloys.At temperatures lower than the B2+O phase field (500 ℃) and higher than the B2+O phase field (1 000 ℃),the joints fracture in the base metal in ductile fracture mode.By contrast,the joints exhibit obvious high-temperature brittleness in the B2+O phase field (650 °C and 800 ℃).Heat treatments were conducted with respect to the thermal history of tensile specimens.Intergranular microcracks along the grain boundary of B2 phase are found in the fusion zone after the heat treatments at 650 ℃ and 800 ℃.The high-temperature brittleness at 650 ℃ and 800 ℃ is attributed to the B2→O transformation along the grain boundary.The stress concentration caused by the volume change of B2→O transformation also contributes to the high-temperature brittleness of laser welded Ti-22Al-25Nb joints.
文摘质量控制经历了检验质量控制、统计质量控制和全面质量控制3个阶段。为实现全面质量控制,Juran提出质量源于设计(Quality by Design,QbD),将质量的概念扩展到产品质量活动的各个领域和环节。中药全过程质量控制与质量源于设计等全面质量控制理念的内涵具有内在一致性,为QbD在中药研发和生产中的应用奠定了良好基础。本文提出并阐释了中药全过程质量控制的2个维度,即从研发到生产的产品生命周期维度和从原料到产品的中药产业链维度。总结了中药全过程质量控制在中药材种植加工过程、中药制剂生产过程和中药产品流通过程的应用。
