Gang WU
,
Ning LI
,
Derui ZHOU
,
Kurachi Mitsuo
材料科学技术（英文）
The metal matrix composite coatings of Co-Ni- Al2O3 were studied by electrolytic codeposition of Co-Ni alloys and Al2O3 on a Cu substrate from a sulfamate electrolyte containing Al2O3 particles. It was illustrated from the examined results of SEM, AFM and XRD that surface morphology and microstructure of Co-Ni- Al2O3 coatings appear to be mainly influenced by variations in Co content. The high Co content coatings with hcp lattice structure have a more uniform and fine structure than that of low Co content coatings with fcc lattice structure. The codeposition of Al2O3 particles in Co-Ni alloys can not change the phase structure of solid solution, only affects the growth and orientation of crystal planes and mostly increase the d value of lattice.
关键词:
Electroforming
,
null
,
null
,
null
Yuhua WEN
,
Ning LI
,
Mingjing TU
材料科学技术（英文）
The effects of prestrain and annealing temperature on phase transformation temperatures in Fel4Mn5Si8Cr4Ni shape memory alloy have been studied. The results showed that when the annealing temperature was 673 K, both the A(f) and the M-s temperatures increased appreciably as the prestrain increased, the A, temperature increased slightly with increasing prestrain, the resistivity difference at 303 K between the heating and cooling curve also increased with increasing prestrain, which agreed with the recovery strain. The shape memory effect in Fe-Mn-Si-Cr-Ni shape memory alloy is caused by the stress-induced gamma --> epsilon martensite transformation and its reverse transformation. When the prestrain was 10%, the M-s temperature decreased remarkably as the annealing temperature increased.
关键词:
Yuhua WEN
,
Ning LI
,
Mingjing TU
材料科学技术（英文）
The effects of aging temperature on shape memory effect, mechanical properties and microstructure of Fe-14Mn-5Si-8Cr-4Ni-0.2C shape memory alloy have been studied. The results showed that the second phase particles rich in chromium, manganese and silicon precipitate during aging, and thereby increase the hardness and strength of the alloy. The shape recovery ratio can be remarkably improved by aging and a maximum value can be obtained at 1223 K, which is 68% higher than that of the specimen in solid solution state. When the aging temperature is below 1223 K, the amount of second phase particles increases as the aging temperature increases. The size of austenite grain increases with increasing aging temperature. When the temperature is over 1223 K, the second phase particles can not precipitate. The lack of second phase particles and the increase of grain size make the hardness and shape recovery ratio drastically decrease, when the temperature is over 1223 K.
关键词:
