Densification and grain growth during isothermal sintering of Mo and mechanically alloyed Mo–TZM

Mo–Zr and Mo–Ti alloy were fabricated by adding alloying element Zr, Ti in molybdenum via powder metallurgy process. The effect of Zr, Ti alloying elements on the tensile strength and microstructure of molybdenum are investigated. Two types of alloying additives are used: one is elemental powder of Zr or Ti; the other is their respective hydride powders, TiH2 or ZrH2. The experimental results show that the formed Mo–Zr, Mo–Ti alloy possess much higher mechanical properties than pure sintered molybdenum. The tensile strength of Mo–Zr alloy is more affected by adding elemental Zr powder than ZrH2 powder, the optimal tensile strength is obtained with addition of 0.1 wt% Zr, most of Zr forms Zr-oxide existed both inside the grain and at the grain boundaries, while very little Zr diffuses into the Mo matrix. Meanwhile, for Mo–Ti alloy, the tensile strength is more influenced by addition of TiH2 powder than elemental Ti powder, the tensile strength is optimized at the content of 0.8 wt% TiH2, some Ti diffuses into molybdenum and forms Mo–Ti solid solution and some forms as MoxTiyOz oxide particles uniformly distributed at the grain boundaries.

Effect of alloying elements Ti, Zr on the property and microstructure of molybdenum

Hot deformation behaviour of Mo-TZM and understanding the restoration processes involved

Effect of filler on the oxidation protective ability of MoSi2 coating for Mo substrate by halide activated pack cementation

Titanium, zirconium and molybdenum (TZM) alloy with different amounts of rare earth lanthanum oxide was prepared by powder metallurgy into 0.5 mm thick sheets. The effects of the La2O3 content on recrystallization temperature and mechanical properties of the TZM alloy were studied. La2O3 increased the recrystallization and recovery temperature of the TZM alloy and increased its tensile strength and elongation.

La2O3 effects on TZM alloy recovery, recrystallization and mechanical properties

The present study describes the effect of thermomechanical treatments on the microstructure of molybdenum–titanium and the molybdenum alloy TZM (0.5 wt.% Ti, 0.08 wt.% Zr). These alloys were processed by a powder metallurgical route including extensive rolling at temperatures above 1200 °C achieving deformation degrees of 2.87 (logarithmic). The alloys exhibit a distinct increase in yield stress without decreasing elongation at fracture. To study the recrystallization behaviour, several samples were annealed at temperatures between 1100 °C and 1600 °C for 15 min until 6 h. The microstructure was examined by scanning electron microscopy (SEM), electron backscattering diffraction (EBSD) and transmission electron microscopy (TEM). Strain rate controlled tensile tests and Vickers hardness measurements are used to determine the mechanical properties. In both alloys a distinct substructure containing subgrains is formed during deformation. A kind of (sub)grain refinement was considered to be responsible for hardening. Present particles are able to raise the recrystallization temperature and thus sustain the grain size effects even at working temperatures above 1200 °C.

Hardening mechanisms and recrystallization behaviour of several molybdenum alloys

Using constitutive equations, the activation volume of the particle- and solid solution hardened Molybdenum alloy TZM (Titanium–Zirconium–Molybdenum) was determined by strain rate jump tests to be 130 ± 20 b 3 at approximately 575 ± 48 K, which is comparably high for bcc materials. Furthermore, through this investigation method, other mechanical properties of the thermally activated motion of dislocations in this cubic body centred alloy were additionally determined, such as the height and shape of the Peierls–Nabarro-potential and the activation energy.

U. Martin

Papers

Hardening mechanisms and recrystallization behaviour of several molybdenum alloys

Thermally activated flow stress component of the Mo alloy TZM determined by constitutive models