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Lanthanum-doped titanium-zirconium-molybdenum (La-TZM) alloy was prepared by powder metallurgy and rolling process. The processing crack and crack initiation mechanisms of La-TZM alloy after sintering, hot rolling and cold rolling were studied by scanning and transmission electron microscopy. The results show that the doped La(NO 3 ) 3 , TiH 2 and ZrH 2 have finer secondary phase in the La-TZM alloy plate. The fracture mode of sintering billet is inter-granular, but the fracture surface of hot rolling exhibited transgranular cleavage. However, the cold rolling is quasi-cleavage fracture. The secondary phase particles tend to hinder the movement of dislocations causing dislocations pile-up. The resulting tensile stress can accelerate cracks nucleation and growth, and the crack propagation will be deflected by the secondary phase particles. The crack initiation can be avoided by reducing local stress concentration caused by dislocations. [ABSTRACT FROM AUTHOR]

Pure molybdenum sheets were prepared by powder metallurgy and unidirectional rolling process. The microstructure, texture, grain orientation, mechanical properties and fracture mechanism of sintered samples were investigated. The results show that tensile strength and microhardness of 95% rolled sheet are 1028.095 ± 19.32 MPa and 323.2 ± 11.68 HV. The main texture components of (011)〈110〉 is Goss texture with reduction in the range of 70–95%. Two grain orientations of 〈111〉 fiber & 〈100〉 fiber and 〈100〉 fiber & 〈110〉 fiber are formed in the 47% and 95% rolled molybdenum sheets, respectively. Meanwhile, the fiber structure become more refined and oriented in the rolled molybdenum sheets when the rolling reduction is >87%. Brittle characteristics show typical cleavage failure. • Tensile strength and microhardness of 95% rolled sheet are 1028.095±19.32 MPa and 323.2±11.68 HV. • The main texture intensity value of Goss texture is 9.52 in the 95% rolled sheet. • Two grain orientations of <111> fiber & <100> fiber and <100> fiber & <110> fiber are formed in the 47% and 95% rolled molybdenum sheets, respectively. [ABSTRACT FROM AUTHOR]

Molybdenum powders were high-energy ball milled for 3, 6, 9 and 12 h respectively, using two ball milling methods: (1) dry milled in vacuum and (2) wet milled in mixed solution of ethanol-polyethylene glycol. The effect of high-energy ball milling on relative density of titanium-zirconium-molybdenum (TZM) alloy was investigated. Particle size distribution and calculated proportion in each size range were designed according to the Dinger-Funk model, reaching the dense packing state. The effects of three different kinds of carbon source (graphite, stearic acid (C 18 H 36 O 2 ) and carbon nanotubes (CNTs)) on oxygen content and relative density were analyzed. The effects of carbon source on oxygen content were studied. After high-energy milling, fine molybdenum alloy powder particles and large amounts of dislocations and vacancies are helpful to improve TZM alloy density during solid sintering process. Doping carbon nanotubes (CNTs) into the TZM alloy as carbon source can improve its density and decrease oxygen content, which is more effective than graphite or stearic acid as carbon sources. Higher TZM alloy relative density results in lower oxygen content. [ABSTRACT FROM AUTHOR]