Tensile behaviour of doped tungsten wire at elevated temperatures

Manu$

Processes,

Vol 10, No 3, 1995,

473.

An unusual morphology in 200 pm Cu powder, milled for long times is reported. The powders granulated and were 1 mm after 3 hours, 3 mm after 60 and 5 mm after 222 hours. The 3 hour granules were solid with pores and cracks. After 60 hours the granules were hollow with residual porosity in the walls. After 222 hours the hollow shells contained secondary hollow

492. A study of t,urning of carbon and stainless steels with tools with a chamfered main cutting edge is described. A force model for a single point tool is constructed which could be applied to the design of tools made with a built-up edge. Tool holder design is discussed and

granules.

It

experiments

granules

could

is

suggested

form

that

after

tertiary

further

with

are described. force, related

milling.

tools

of differing

Measurements of cutting to cutting speed and tool

Iron and steel

angle were reported to agreement with predictions.

MECHANICAL PROPERTIES OF HIGH VACUUM SINTERED IRON-SILICON ALLOYS

secondary

M.

Seleka

et

Sciences,

al.

Kosice,

kwve Metahrgie, Czech.) An Fe and

of Fe-4.5XSi ferro-Si

700 MPa, llOO-125O’C

the

(In

of powder

made

at

sintering at is described.

characteristics

245

are

reported.

The

results

are

MICROSTRUCTURE

28,

hour

with

l/2,

Academy of Meta/. Prosz-

1995,

0.2 to 0.6!‘#

at 1200°C

in either

21-25.

sintered

(In

effect

for

vacuum,

NHcj or N-25’%H. N is shown the denshying

1

The 12%Cr

investigated.

MADE

nitriding steel

by open 5% open

that

of a were

compact.

Only

treatment

with

the

OF PHOSPHORUS

ADDITION SINTERED

ALLOY

ON PROPERTIES MOLYBDENUM

National

(Yatsushiro

Yatsushiro, Japan). J. Japan and Powder Metallurgy, Vol

College

41, No 4. 1994, 467-461. (In Japanese.) Sintering of MO powder with addition It is reported

enhanced to

Quenching

and

of temperatures,

that

densification.

the

formation

of

powder, the

This of

a

is

liquid

decomposed

on

made are

K.H.

Fuh,

tempering,

were

at a

used. STEEL

CHAMFERED

Japan).

.J, Japan

Metalhrgy,

a range

annealed castings. than for castings

of compacted

Ti alloys have similar to those of

Fatigue limits are higher but inferior to wrought

Porosity is reduced and improved by thermal cycling.

AND

OF TITANIUM

Japanese.) It is reported material, particles,

that

a TiAl

reinforced had been

pressing.

Some

particulates particles

and with

reaction

or R,C by hot between

matrix was reaction

homogeneously

composite

with SIC fabricated

detected. The zones were

dispersed

improvements

in properties

Structure/property

are

and reported.

relationships

are

Chang

TENSILE BEHAVIOUR OF DOPED TUNGSTEN WIRE AT ELEVATED

WITH

MAIN

studied cubic

(Tatung

Taiwan).

Inst. Mater.

of and

(Jniversity,

Fukuoka,

Sot. Powder and Powder

Vol 41, No 4, 1994, 462-467.

with

(In

K.

Fujii

Fukuoka,

et

al.

(Nippon

Tungsten

Co,

Japan),

Nippon

Tungsten

Rev.,

properties

of W

Vol 27, 1995, of Tii (2 to 4)wtWr reference

transformations.

relationships,

Taipeh,

that

TEMPERATURES et al. (Kyushi

Japanese.) Sintering

EDGE C.S.

No 1, 1993, 28. (In Russian.)

Tungsten

Y. Ikeda

treatment, Technology,

Masckin.,

discussed.

University

alloys, powder.

OF STAINLESS

WITH

Moscow,

i Teknol.

Japan). J. .Japan Sot. Powder and Powder Metallurgy, Vol 41, No 5. 1994, 514-517. (In

of Technology, Sot. Powder

of NIP or FeP alloy

(Moscow

ALUMINIDE MATRIX COMPOSITES A. Nakahira et al. (Osaka IJniversity, Osaka,

OF COMPACTS

T. Sakamoto

investigated.

TITANIUM

Inst.,

MICROSTRUCTURES

on properties

of three sintered Fe-Cu-Mo from Fe-1.5% prealloyed

CUTTING

is

of final

Mai’skdya.

,Voic,vyr Mater.

Russia).

Composites

on cooling. Repressing enhances strength.

ALLOYS

TOOLS

E.Y.

Technological

martensitic martensite

Spanish.) Effects

TURNING

Iiazimov,

materials. properties

MICRO-DUPLEX TREATMENT OF SINTERED TITANIUM-CHROMIUM

range

properties

OF POWDER

It is reported

surface

of Madrid. Madrid, Spain). Rehta Metal. Madrid, 1’01 31. No 2, 1995, 71-77. (In

evaluated.

powders

POWDERS

et al. (Polytechnic

of heat

conditions on arc presented.

and vacuum sintered mechanical properties

Titanium J.M. Torralba

OP.

nitriding

pores reaching porosity right

phase. The P compound formation of the liquid.

PREALLOYED

IRON-MOLYBDENUM

process products

of Ti and Ti alloy

Vol

Pressing sintering and post treatments are discussed. of powder characteristics and

Aviation

It is reported

the

addition

OF SINTERED

FROM

Production described. sintering Influences

nitriding occurs if the porosity is closed. N is an austenitr stabilizer and the steel is austenitic at nitriding temperture becoming

was

to counteract

Gorniczo-Ilutnic-

SOC. Powdw

Vol 41, No 4, 1994,

effects of pores on ferritic stainless

P, in the form

cracked

of B.

TREATMENT

STEEL

(Akademia

ALLOYS

lJniversity,

(In Japanese.)

attributed HEAT

(Kyushi

J. fJapan

Japan)

EFFECT

No

S. Szczepanik

za, Krakow, Poland). Metal. Proszkow, 28 No l/2, 1995, 26-38. (In Polish.)

PROPERTIES

An evaluation of B as a sintering enhancer is described for Fe and Fe-B’%Ni0.5%Mo

al.

IN DIFFERENT

M. Seleka et al. (Slovak Sciences, Kosice, Slovakia). kou:, Vol English.)

et

Molybdenum

OF IRON-BORON

OF HIGH DENSITY FROM TITANIUM ALLOY

PROPERTIES N. Nakamura

through

discussed with regard to the effects of surface oxide dissociation during vacuum sintering.

ALLOYS SINTERED ATMOSPHERES

OF

PRODUCTION MATERIALS POWDERS

COMPACTS

is enhanced 0.26wtXN at

and

process conditions were determined. Maximum values of 97.8% density, tensile strength of 718 MPa and Vicker’s hardness of

STEEL

468-473.

from

by compaction

vacuum 1-4 hours,

are considered.

and Powder Metallurgy,

mechanical

alloys,

powders,

and for

effects

of

Fukuoka. of

formation

good and

Prcw

28-46.

1994,

chip

be in Primary

EFFECTS OF PORES ON NITRIDING CHROMIUM FERRITIC STAINLESS

Academy Pokroky

No 4,

investigation

properties

The

(Slovak

Slovakia).

design

annealing in the r’+ p region gives the duplex structure. This is reported to have good mechanical properties.

as are

to

alloys

was

hexagonal

to

Structure/property functions

established.

of

heat

Quenching

from the single p phase condition results in formation of ry’ phase and subsequent

High

l-9.

temperture

tensile

wire, doped with different different grain sizes, were H or N. Fractures brittle to 0 increase

were

in N. The differences content. Strength

‘%;K and with investigated in

ductile

in H and

are attributed increased with

in %K.

MPR February

1996

39

MANUFACTURE

TO NEAR-NET

OF TUNGSTEN-COPPER

SHAPE

COMPOSITES

Y. Kai et al. (Nippon Tungsten Co., Fukouka, Japan). Nippon Tungsten Rev., Vol 27, 1995, 10-17. Production of W- (10 to 40) %Cu parts, to close dimensional tolerances, by liquid phase sintering or Cu infiltration was investigated. It is reported that parts could be made in W-(15 to 27)YKu with minimal shrinkage from a blend of 1 and 8 urn powder and infiltration.

Hard materials and too/ steels A HISTORY OF FINE-GRAINED HARDMETALS G.E. Spriggs (Rusheen, Castlemain, Ireland). Znt. J. Refi-uctory Metals and Hard Muteriuls, Vol 13, No 5, 1995, 241. 255. The scientific and technological development of fine-grained hardmetals historically

reviewed. 1929 is noted as the

year of identification

Electrical and magnetic ma teriak

the particle size which can be produced. The role of milling is discussed with reference to uniformity of compacts and inhibition of grain growth during sintering

of some aspects of WC

grain refinement and by 1939 the beneficial grain relining effects of VC and TaC had been established. Changes in the definition

A TECHNICAL ECONOMIC ANALYSIS OF MAGNETS AND MAGNETIC MATERIALS

of ‘fine’ are considered, going from pm sizes in early years to nm sizes more recently. The author asks if this is the end of the story.

T. Abraham

APPLICATION

(Business Communications

Co,

Norwalk, Connecticut, USA). Int. J. Powder Metullurgy, Vol 31, No 2, 1995, 133-136. The commercial magnetic magnet

CARBIDE BASED CARBIDES

status of hard and soft

materials is reviewed. Permanent alloys

TUNGSTEN CEMENTED

OF FINE-GRAINED

considered

included

hard

L.J. Prakash (PM Pulvermetall GmbH, Rottenburg, Germany). Znt. J. Refructory Me-

ferrites, Sm-Co, Fe-Nd-B and Alnico. Soft materials were Fe-% electrical steels,

tals und Hard

amorphous

It is noted that sub-micron grade cemented carbides account for 10.15% of

feromagnetic

It is considered

alloys and Fe-Ni.

that

with

continuous

further improvements numerous applications will be found.

novel

1995, 257-264.

the market being characterized

properties

of Science, Beijing,

PM Technology, Vol 13, No 1, 1995,

3-7. (In Chinese.) It is reported that Ar atomized Fe-Nd-B powder consisted of a tetragonal NdzFe,,B phase. The compared

magnetic properties with powder made

comminution

of cast material

MECHANISM OF IMPROVEMENT CORROSION RESISTANCE OF TERNARY NEODYMIUM-BORON

are by

OF

Corporation,

Chiba, Japan).

DIFFUSION

BONDING

CARBIDE ON TO NODULAR CAST IRON BY HOT ISOSTATIC PRESSING C. Feixiong,

L. Shikui

(Central

Iron and

Steel Research Inst., Beijing, China). PM Technology, Vol 13, No 1, 1995, S-13. (In Chinese.) reported of

that

direct

cemented

diffusion

carbide

on

to

and

the

characteristics

bond are

(In

between

phases

in

At pH above 5.8 by a passive film.

performance described. modulus

of bonded

diamond

It is reported is a controlling

TERMINOLOGY

Young’s

factor in bonding.

TESTING

IMAGING AND MODELS GRAINED HARDMETALS B. Roebuck Teddington,

tools are

that

PROPERTIES FOR FINE-

(National Physical Laboratory, Middlesex, UK). Znt. J. Kefiac-

tory Metals and Hard Materials, Vol 13, No 5, 1995, 265-279. The hardness of WC hardmetals, particle

for

size

and

powders

of

and

it

relative

availability

is discussed.

standardization

emphasized

the

of

The need

terminology is

noted

is that

improvements in the technology of testing and characterization are required. These issues and models for prediction of hardness and magnetic properties from grain size are considered,

the Hall-Petch

relationship in particular. The use coercivity measurements for estimation

of of

grain

in

size

and

the

are are

caution

mentioned.

critically

needed

Published

reviewed

with

regard to the need for standardization

of

for grain size measurement. OF BORON CARBIDE

MANUFACTURE

S.M. Joo et al. (Chungnam

National

lltri

tory Metals and Hard Materials, Vol 13, No 5, 1995, 281-296. Aspects and liquid

of powder production, milling phase sintering of WC based

Synthesis of B,C was investigated a11(1is shown to be possible by reacting :! 1i;ir.l~

materials

are

BzO:r, 6 to 7 parts Mg and 1 to 1.4 parts 01’ C. The B,C particles are showu IO I),* spherical and pure. ParticI(b si/.cb is

production

to be more effective than Co against pitting.

particle

of

discussed. WC

are

growth considered.

that 50-150 nm represents

1996

bonding

versity, Daejeon, Korea). J. Korean Ztrsl. u/’ Metals, Vol 32, No 10, 1994, 1243-1249. (III Korean.)

Keplacement of Fe by Ni and Co enhances corrosion resistance at pH2.7. Ni is shown

MPR February

of

FROM OXIDE BY SELF-PROPAGATING HIGH TEMPERATURE SYNTHESIS

W.D. Schubert et al. (Technical University of Vienna, Vienna, Austria). Znt. J. Refiuc-

40

and

mechanisms

cutting performance. Investigations of mechanical properties and cutting

PREPARATION

ASPECTS AND LIMITS OF ULTRAFINE TUNGSTEN CARBIDE POWDER AND

Ni-Ti) -B magnets had been elucidated with some improvements made. These are attributed to small differences in of pH2.7. is inhibited

chemical

methods

HARDMETAL

solutions corrosion

with the is and

equations

described fracture

powder

matrix in cutting tool materials discussed with respect to physical

structures

It is reported that the mechanism of corrosion resistance of sintered Nd- (Fe-Co-

potential

449-453. (In Japanese.) Bonding of diamond

extrapolation

are

ON

OF

T. Fujimori et al. (Chiba Inst. of Technology, Narashino, Japan). J. Japan Sot. Powder and Powder Metallurgy, Vol 41, No 4, 1994,

nodular cast iron had been achieved by HIP using Ni foil as an interlayer. Interface strength and evaluated.

OF THE MATRIX

CUTTING PROPERTIES DL4MOND TOOLS

ultraline

OF CEMENTED

OF MECHANICAL

J. Japan Inst.

ofMetals, Vol 59, No 2, 1995, 206-212. Japanese.)

corrosion

EFFECT

PROPERTIES

to

bonding

(Kawasaki Steel

to result in

service lives of components.

It is

MAGNETS Y. Fukuda, M. Shimotomai

by a balance

to use is reported

increased

China).

13, No 5,

materials as well as forming tools and in wear resistant applications. Matching

IRON-NEODYMIUM-BORON

0. Tong et al. (Academy

Vol

between hardness and toughness. The materials are used for cutting a wide range of metallic and non-metallic

MICROSTRUCTURE AND HARD MAGNETIC PROPERTIES OF ATOMIZED POWDER

Materials,

by addition of VC. Grain growth in the solid state is considered. Discontinuous grain growth in ultraline materials is noted. It is suggested that there is a lower limit of ZOO-300 nm for the grain size of WC and that finer sizes can only be attained by completely new technology.

Methods reviewed

of and

It is suggested a lower limit to

reduced by increased

reaction

liressrii~(~.