The phrase "a secondment to" is correct and usable in written English.
It is typically used in a professional context to refer to a temporary transfer of an employee to another position or organization.
Example: "She accepted a secondment to the London office for six months to gain international experience."
Alternatives: "a transfer to" or "an assignment to".
He retired in 1990, after a secondment to the Canadian Museum of Civilisation.
Following a secondment to Northern Engineering Industries, Carless served until his retirement, in 1985, as ambassador in Caracas.
She had been appointed as a peer in 1999 while on a secondment to the home office.
Unhappy at returning to Europe when his tour of duty was over, he successfully applied for a secondment to the Muscat regiment.
This involved much travel and included a secondment to Tehran for the planning of an Iranian "open university" in the last year of the Shah's reign.
The pair are separated when Stu's literary abilities secure him a secondment to the forces' weekly magazine, Yank, something of a haven for gay men, where Stu flourishes under the mentorship of a defiantly out photographer named Artie.
* He joined the BBC as a studio manager in 1979 and took up a British Forces Broadcasting Services secondment to the Falklands.
"Lastly, we continue to fund a £50,000 secondment to the Office for the Coordination of Humanitarian Affairs to support the coordination of humanitarian assistance.
Ingeus Deloitte was announced as the Government's preferred provider for seven major welfare-to-work projects, but concerns were raised that Mr Grayling received £27,978 in kind from a staff secondment to his office in 2009.
Paul Collingwood, whose final match for England was in Chittagong three years ago, but who has a temporary secondment to the England team as assistant coach to Ashley Giles, was nominated as a substitute fielder for the first one-day international between England and West Indies in Antigua.
Andy Farrell enjoyed a successful secondment to England duty from Saracens and Mike Catt is now due to be another short-term appointment as backs/attack coach.
