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Evolution of microstructure and phase composition of Ti-3Al-5Mo-4.5V alloy with varied β phase stability

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Journal of Materials Science & Technology 2018年第12期34卷 2325-2330页

作者： Q.Xue Y.J.Ma J.F.Lei R.Yang C.Wang School of Metallurgy Northeastern University Institute of Metal Research Chinese Academy of Sciences

The microstructure evolution and phase composition of an α+β titanium alloy, Ti-3Al-5Mo-4.5V(wt.%),have been investigated. Electron probe micro analysis(EPMA) quantitative results manifest that the stability of β phase decreases with increasing quenching temperature, which is influenced by the significant variation of β-stabilizing elements concentration. Detailed microstructure analysis shows that the β→ωphase transformation does occur when quenching at 750℃ and 800 ℃. The ω-reflections change from incommensurate ω-spots(750 ℃) to ideal ω-spots(800 ℃) as the β stability of the alloy decreases. Further the decrease of β phase stability encourages the formation of athermal α " martensite, which has the following orientation relationships: [111]β//[110]α",[100]p//[100]α " and [-110]p//[00-1]α" with respect to the β matrix.

关键词： Dual-phase titanium alloy β phase stability ω phase α" martensite Microstructure

Review on ω phase in Body-Centered Cubic Metals and Alloys

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Acta Metallurgica Sinica(English Letters) 2014年第1期27卷 1-11页

作者： Dehai Ping National Institute for Materials Science Sengen 1-2-1Tsukuba 305-0047Japan

An ω phase with a primitive hexagonal crystal structure has been found to be a ωmmon metastable phase in body-centered cubic （bcc） metals and alloys. In general, ω phase precipitates out as a high density of nanoscale particles and can obviously strengthen the alloys; however, ωarsening of the ω particles significantly reduces the alloy ductility. The ω phase has ωherent interfacial structure with its bcc matrix phase, and its lattice parameters are aω ---- x/2 x abcc and ωbcc= v/3/2 abcc abet. The ωmmon { 112} （111）-type twinning in bcc metals and alloys can be treated as the product of the ω ~ bcc phase transition, also known as the ω-lattice mechanism. The ω phase＇s behavior in metastable 13-type Ti alloys will be briefly reviewed first since the ω phase was first found in the alloy system, and then the existence of the ω phase in carbon steels will be discussed. Carbon plays a crucial role in promoting the ω formation in steel, and the ω phase can form a solid solution with various carbon ωntents. Hence, the martensitic substructure can be treated as an ct-Fe matrix embedded with a high density of nanoscale ω-Fe particles enriched with carbon. The reωgnition of the ω phase in steel is expected to advance the understanding of the relationship between the microstructure and mechanical properties in bcc steels, as well as the behavior of martensitic transformations, twinning formation, and martensitic substructure.

关键词： ω phase Martensitic steel Microstructure Microanalysis bcc metals Alloys Twinning

Effects of Ce and Ti on the microstructures and mechanical properties of an Al-Cu-Mg-Ag alloy

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Rare Metals 2007年第1期26卷 28-32页

作者： SONG Min CHEN Kanghua HUANG Lanping State Key Laboratory of Powder Metallurgy Central South University Changsha 410083 China

The effects of Ce and Ti additions on the microstructures and mechanical properties of an Al-Cu-Mg-Ag alloy have been studied, It has been shown that either Ce or Ti can decrease the as-cast grain size of the Al-Cu-Mg-Ag alloy, increase the nucleation ratio for ω phase as heterogeneous nucleation centers, inhibit the growth of ω phase during aging, and thus increase the volume fraction and decrease the spacing of ω phase. These microstructures increase the yield strength and tensile strength. However, if both Ce and Ti are added to the alloy, they form （Ce,Ti）-contained compounds and increase the grain size during casting, but have no effects on the nucleation and the growth of ω phase during aging. The alloy containing both Ce and Ti has a relatively lower Vicks hardness and strength compared to the alloy containing either Ce or Ti.

关键词： Al-Cu-Mg-Ag alloy microstructures mechanical properties Ce Ti ω phase