Honglian DAI
,
Shipu LI
,
Yuhua YAN
,
Xianying CAO
,
Xuehui LU
,
Yang LENG
材料科学技术（英）
To study the osteogenesis and transformation process of calcium phosphate bioceramic in vivo, biodegradable porous beta-tricalcium phosphate ceramics (β-TCP, 5×8 mm) were implanted in the tibia of rabbits. β-TCP ceramics with surrounding bone tissue were retrieved and observed by SEM, TEM and EPMA every month after implantation. The results showed that osteogenesis was active and β-TCP ceramics bonded to bones directly. The new bones were forming and maturing as materials were continuously degrading, and materials were finally replaced by new bone. Parts of the materials were degraded, absorbed and recrystallized, while the rest were dispersed to the spongy bone and the Haversian lamella in an irregular arrangement, becoming incorporated into bone formation directly by remodeling the structure. Some β-TCP crystals cleaved along its (001) rhombohedral plane and formed lath-like crystals in vivo.
关键词:
Calcium phosphate ceramics
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null
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null
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null
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Qiming DONG
,
Dongmei ZHAO
,
Ping LIU
,
Buxi KANG
,
Jinliang HUANG
材料科学技术（英）
Age hardening in Cu-3.2Ni-0.75Si(wt pct) and Cu-1.0Ni-0.25Si (wt pct) alloys from 723 to 823 K is studied. After an incubation period strengthening appears which is due to precipitates in the Cu-1.0Ni-0.25Si (wt pct) alloy. On other hand an immediate increase of the yield strength characterizes the aging of the alloy. This is followed by the regions of constant yield strength and further by a peak. The microstructure of the alloy was studied by, means of transmission electron microscope (TEM) and X-ray diffraction (XRD). Spinodal decomposition takes place followed by nucleation of the ordering coherent (Cu,Ni)3Si particles, further precipitation annealing coherent δ-Ni2Si nucleated within the (Cu,Ni)3Si particle. Any change of the yield strength can be described by an adequate change of the structure in the sample. The nature of the aging curves with a "plateau" is discussed. The formulas of Ashby and Labusch can be used to explain the precipitation.
关键词:
Copper alloy
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null
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null
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null
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null
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null
Xiaopeng LIU
,
Wei JIN
,
Mingzhou CAO
,
Dazhi YANG
,
Feixia CHEN
材料科学技术（英）
Compared with the undeformed TiNi film, the martensite-austenite transformation (M-A) of the deformed one is elevated to a higher temperature on the first heating, but it nearly returns back to the original temperature on the second heating. An incomplete M-A transformation of the deformed TiNi film on the first heating divides the total martensite population into the self-accommodating martensite M2 and the oriented martensite M1. Thus, two transformations corresponding to M1-A and M2-A transition occur on the second heating. However, the forward transformation is not affected by the incomplete thermal cycle.
关键词:
TiNi film
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null
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null
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null
Furen XIAO
,
Mingchun ZHAO
,
Yiyin SHAN
,
Bo LIAO
,
Ke YANG
材料科学技术（英）
Acicular ferrite microstructure was achieved for an ultralow carbon pipeline steel through the improved thermomechanical control process (TMCP), which was based on the transformation process of deformed austenite of steel. Compared with commercial pipeline steels, the experimental ultralow carbon pipeline steel possessed the satisfied strength and toughness behaviors under the current improved TMCP, although it contained only approximately 0.025% C, which should mainly be attributed to the microstructural characteristics of acicular ferrite.
关键词:
Pipeline steel
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null
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null
Wei JIN
,
Mingzhou CAO
,
Rui YANG
,
Zhuangqi HU
,
Shaoyu QIU
,
Hong ZOU
材料科学技术（英）
The effect of heat treatment on martensitic transformation behavior has been investigated in Ti44Ni47Nb9 alloy. The relation between transformation temperatures and critical stress of stress induced martensitic transformation is interpreted in terms of thermodynamic theory. It is shown that the decrease in transformation temperature in specimens of slow cooling rate or low temperature aging after solution heat treatment results from the changes of Ni/Ti ratio in the matrix. The increase of critical stress of stress induced martensitic transformation is a consequence of the decrease of transformation temperatures.
关键词:
Ti44Ni47Nb9 shape memory alloy
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null
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