Refractory Metal Mo-La · heat-treated state
Refractory Metal Mo-La-RX
Properties of the RX condition, compared with the other Mo-La tempers.
Represents the property floor after long high-temperature service; ML keeps a fine elongated grain structure so it stays far tougher than recrystallized pure Mo.
What is Mo-La-RX?
Mo-La-RX is Mo-La heat treated to RX — represents the property floor after long high-temperature service; ML keeps a fine elongated grain structure so it stays far tougher than recrystallized pure Mo. Mo-La-RX has a yield strength of 310 MPa (45 ksi) and a tensile strength of 450 MPa (65.3 ksi) — weaker than 56% of refractory metal grades. Elongation at break is 22% and the elastic modulus is 320 GPa (46.4 Msi). Mo-La-RX has a density of 10.2 g/cm³ (0.368 lb/in³), heavier than 63% of refractory metal grades. It melts at 2,620°C (4,748 °F). As Rolled is the default condition FabDigit quotes; RX is available on request or by drawing note.
Advantages
- Easy to machine — 45/100, better than 99% of refractory metal grades
- High service temperature — 1,800°C (3,272 °F), better than 91% of refractory metal grades
- Conducts heat well — 125 W/m·K (72.2 BTU/hr·ft·°F), better than 85% of refractory metal grades
- High electrical conductivity — 30 % IACS, better than 84% of refractory metal grades
- Stiff — 320 GPa (46.4 Msi), better than 82% of refractory metal grades
Limitations
- Difficult to weld — 20/100, worse than 79% of refractory metal grades
Mo-La-RX properties
Typical room-temperature values for Mo-La-RX — 8 properties are specific to this condition; the rest are grade-level values shared by every Mo-La temper. Each bar shows where the value sits among the refractory metal grades in FabDigit's library — further right is higher.
Physical3
Mo-La-RX has a density of 10.2 g/cm³ (0.368 lb/in³), heavier than 63% of refractory metal grades. It melts at 2,620°C (4,748 °F).
Mechanical11
Mo-La-RX has a yield strength of 310 MPa (45 ksi) and a tensile strength of 450 MPa (65.3 ksi) — weaker than 56% of refractory metal grades. Elongation at break is 22% and the elastic modulus is 320 GPa (46.4 Msi).
Thermal6
Mo-La-RX is rated for continuous service to 1,800°C (3,272 °F). It conducts heat at 125 W/m·K (72.2 BTU/hr·ft·°F), better than 85% of refractory metal grades. Thermal expansion is 5.3 µm/m·K (2.94 µin/in·°F).
Electrical3
Mo-La-RX conducts electricity at 30 % IACS, better than 84% of refractory metal grades.
Chemical & Environmental3
Corrosion resistance is good (55/100), worse than 74% of refractory metal grades.
Sustainability4
Producing a kilogram of Mo-La-RX takes about 380 MJ of energy and emits 25 kg of CO₂ — less than 77% of refractory metal grades. Typical recycled content is 25%.
Manufacturability7
Mo-La-RX's machinability is fair (45/100, better than 99% of refractory metal grades); weldability poor (20/100); formability fair (35/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other Mo-La tempers and conditions
Mo-La is also supplied in 5 other conditions. The full side-by-side table is on the Mo-La overview.
- As RolledDefaultStandard stocked condition for ML sheet, plate and foil: highest as-supplied strength with usable room-temperature bend ductility.560 MPa yield · 240 HV
- RXRepresents the property floor after long high-temperature service; ML keeps a fine elongated grain structure so it stays far tougher than recrystallized pure Mo.310 MPa yield · 170 HV
- As SinteredCheapest form for crucibles, blanks and machined-from-solid parts where residual porosity and low ductility are acceptable.300 MPa yield · 180 HV
Working with Mo-La-RX
Is Mo-La easy to machine?
Machine with sharp positive-rake carbide or PCD at moderate speed and generous feed, flood coolant, and preheat/warm the part for tapping or thin-wall turning to avoid chipping and edge cracking.
Can Mo-La be welded?
Only EB or laser welding in high vacuum/inert gas is practical, and the fusion zone recrystallizes and becomes notch-sensitive — vacuum brazing or mechanical fastening is preferred for load-bearing joints.
Can Mo-La be formed, bent or molded?
Roll, bend and deep-draw warm (about 150–400 °C for sheet, higher for thick stock); keep bend radii ≥3–5 t, and avoid grinding-induced surface cracks that trigger brittle failure.
What surface finishes work on Mo-La?
Chemically clean/pickle or electropolish for vacuum service; for air service above ~500 °C apply a silicide (Si-Mo) or CVD/plasma-sprayed oxidation barrier — plating and anodizing are not used.
Mo-La chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| La2O3lanthana dispersoid; common commercial blends are 0.3 %, 0.7 % (Plansee ML) and 1.1 % | 0.3 – 1.2 | 0.7 |
| Cimpurity limit | ≤ 0.01 | 0.01 |
| Oexcluding oxygen bound in La₂O₃ | ≤ 0.03 | — |
| Feimpurity limit | ≤ 0.01 | — |
| Niimpurity limit | ≤ 0.01 | — |
| Siimpurity limit | ≤ 0.01 | — |
| Mo≥98.8 % balance | balance | — |
Mo-La-RX — frequently asked
What is Mo-La-RX used for?
Mo-La-RX is typically used for furnace heating elements, sapphire crystal-growth crucibles, sputtering targets and backing plates, hot-zone shields and support structures, hot-work tooling for glass and metal forming and drawn wire for high-temperature leads and springs. In short: ductile-improved molybdenum wire.
What is the yield strength of Mo-La-RX?
Mo-La-RX has a typical yield strength of 310 MPa (45 ksi) and a tensile strength of 450 MPa (65.3 ksi) — weaker than 56% of refractory metal grades. Strength varies by condition: see the 6 listed tempers.
Is Mo-La-RX easy to machine?
Reasonably — machinability is rated fair (45/100, better than 99% of refractory metal grades). Machine with sharp positive-rake carbide or PCD at moderate speed and generous feed, flood coolant, and preheat/warm the part for tapping or thin-wall turning to avoid chipping and edge cracking.
Can Mo-La-RX be welded?
Not readily — weldability is rated poor (20/100). Only EB or laser welding in high vacuum/inert gas is practical, and the fusion zone recrystallizes and becomes notch-sensitive — vacuum brazing or mechanical fastening is preferred for load-bearing joints.
What surface finishes work on Mo-La-RX?
Chemically clean/pickle or electropolish for vacuum service; for air service above ~500 °C apply a silicide (Si-Mo) or CVD/plasma-sprayed oxidation barrier — plating and anodizing are not used.
Can Mo-La-RX be formed, bent or molded?
Roll, bend and deep-draw warm (about 150–400 °C for sheet, higher for thick stock); keep bend radii ≥3–5 t, and avoid grinding-induced surface cracks that trigger brittle failure.
What is the maximum service temperature of Mo-La-RX?
Mo-La-RX is rated for continuous use to about 1,800°C (3,272 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Mo-La As Rolled and Mo-La-RX?
As Rolled is the default condition — standard stocked condition for ML sheet, plate and foil: highest as-supplied strength with usable room-temperature bend ductility. RX: represents the property floor after long high-temperature service; ML keeps a fine elongated grain structure so it stays far tougher than recrystallized pure Mo. Yield strength is 560 MPa in As Rolled versus 310 MPa in RX.
Can FabDigit make parts in Mo-La-RX?
Yes — Mo-La-RX is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- Molybdenum-Lanthanum Oxide (ML) material property data — Plansee SE (2023)
- ASTM B386/B386M — Molybdenum and Molybdenum Alloy Plate, Sheet, Strip and Foil — ASTM International (2021)
- ASTM B387 — Molybdenum and Molybdenum Alloy Bar, Rod and Wire — ASTM International (2018)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (Refractory Metals) — ASM International (1990)
- Lanthanated molybdenum sheet, rod and wire product data — Elmet Technologies / Ed Fagan / (2024)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.